My simple question to those who would is "Do you play the game or the Box?*
Google what a video game is and what its meant to do and you will find your anwser there.
My simple question to you is "Do you prefer to buy a product, or a service that you don't control ?"
If your Steam account is closed (for whatever reason, like not accepting a new EULA for example) you loose all your games.
Note : link redirect to a french site, so there is this that is not the same story but seems to have the same result.