Why you shouldn't use Steam
This article goes through the timeline of Steam, a proprietary system developed by Valve, and highlights its harmful effects on its users.
Valve has said that the motivation behind the development of Steam was to make it easier to distribute patches, however, had this been true, the implementation would be different. You can't run a Steam enabled game without running Steam. Steam is a mandatory DRM. When I bought a Half-Life 2 DVD, I couldn't play it because it required an Internet connection, the latest version of Steam and of the game itself. It took me hours to download the latest Steam version and after that it announced that it needed to download a 150 Mb patch. That would've taken take at least 15 hours to download and would've resulted in a huge Internet bill. Why do I need a latest patch to play a single player game? Why an Internet connection for a single player game? Of course, because Valve treats all customers as copyright infringers, guilty until proven innocent. Lucky for Valve, the Half-Life 2 got positive reviews and some people decided to suffer mistreatment to play the game.
Valve Anti-Cheat is a spyware that scans your computer to try detect an unauthorized modification of the game. Not much is known about the it's design since it uses security through obscurity. When you connect to a VAC secured server, you give up your control of your computer. And since VAC is just another program, it has bugs which can lead to false positives and will lock you out from the game. In 2006 Steam installed a special device called "Steamdrv" which could be seen in Device Explorer. This can mean that Valve wanted a Ring-0 access to full internals of your computer.
Valve was not the first company to implement achievements as we know them. However, I'm sure they knew the psychological weaknesses behind them and knew how to exploit them. In 2007 they released Steam Community and one notable thing was that as long as your profile is public, anyone can view your achievements. Well, at least they didn't go all the way and implemented gamerscore (yet). But this is the date when it was certain that Valve is not above abusing any kind of social engineering.
Another notable thing that was introduced was a score that was displayed in your Steam Community page that depended on how much you've played for the past 2 weeks. It would go through 0 for no game time to 10 for 32 hours. This is the first time Valve has used gamification - a system to reduce a human to an animal in a Skinner box and abuse them to no end. I find it peculiar that the term has association with video games because adding in-game rewards is an indication of complete failure at game design.
Some games on Steam have region locks. Usually this means that you can only play the game if your IP address matches the region of the game. This means when you travel abroad, you may not be able to play your games. Sometimes, you have limited options of choosing the language of the game. For example, some games may only be available in the language of the country they were licensed in. Many games released in Germany are heavily censored, though this is also an indication of the general problem with German law. Also, the prices for games may fluctuate heavily. The European and Australian prices and are usually higher than US.
Steam Cloud is a Service as a Software Substitute which was released in 2009 that stores some game data such as saves and other files that are modified during gameplay. There are 2 problems with it. First, the data is not encrypted by the user which means that Valve get to spy on your data. Second, the system itself has very little documentation and it is very difficult to know what exactly to stored and how to manage it. In particular, erasing your data is non-trivial as the Steam may see an empty directory as an indication that the user didn't use Steam Cloud on that machine and automatically download the data from its servers.
Translation server is a little known part of Steam that uses unpaid labor to translate text. You may opt-in for translation and be presented with a text used in Steam to translate. After translating it, your translation will be reviewed and if it's considered good, you'll get "translation points". What can you with translation points? You can request more text to translate and it's a never ending cycle. You get no money for your work while Valve uses it to market its games and gain more profit. Again, gamification is used in here to give you reward which has no actual value but you are trained to think that it has. Don't be a fool.
In 2010 Valve has added microtransactions to Team Fortress 2 making it their first Fee To Pay game. They've added Steam Wallet to handle this. And now that there is a microtransation service, Valve has added a section called "Free To Play" with games that can be downloaded and played free of charge but that require significant financial investment in in-game item shop to achieve anything. Of course, there is no "Free" section because Valve is only interested in milking every cent they can from their users. Since then, Valve has added a substational amount of paid content in their games making people waste huge amount of money for it. This fact has spawned a lot of illegal sites that allow people to trade or otherwise use their in-game items.
Portal 2 was (probably) the first time Valve has used social engineering directly for profit. The users were asked to license random indie games and complete challenges inside them to gain badges on their Steam profiles. This was supposed to help Portal 2 to be released early - also a reward with zero value. Since then, Valve has started to add more rewards which would be seen on the Steam Community profiles.
I have stopped using Steam when trading cards were introduced by it is obvious that this is another Skinner Box. In fact, this led to a rise of games being released only to profit from trading cards.
Steam is a DRM, spyware and is abusing social engineering to make profit by any means possible. When you start using Steam, you give up your control over your computing and opt-in in a Skinner box. Valve has made it clear that they will not stop this and will hold onto it to the end. This means that the only way to solve this is to drive Valve out of business. This is not an easy task and would require a collaboration of many people. Despite all of its bad aspects, Steam has several good ones such as the ability to discover new games and to see what game your friends are playing. We can take these features and implement them in the ethical way using only free software.
How to stop using Steam
For some people most of their game library is inside Steam and making a switch is hard. It took me 3 years from understanding that I must stop using Steam to actually stop using it. This process can be done gradually.
It is possible to permanently remove the games from your account. There are a few steps you need to perform.
Wiping achievements and stats.
Download Steam Achievement Manager and run it. It has a very simple interface and can easily remove all your achievements and stats
Wiping Steam Cloud
Wiping Steam Cloud is harder and I forgot how I did this myself. Search the web.
Uninstall the game
Use Steam GUI.
Contact Steam support
You can remove several games at a time but don't need to remove all games at once. You will need a proof of ownership such as a photo of your Steam key or credit card info. The first line of support will tell you that it's not possible to remove games. You must be persistent and point to Steam Subscriber Agreement that you have the legal right. After that you will be asked for confirmation. The whole process may take a week.
While SSA says that is possible to remove your Steam account, some information will be kept forever. When I contacted support to delete my account, they first removed my email from my account but I still could login. Second request fixed it but my Steam community profile, while being private, was still viewable.