aaaand dont forget about the anoying "updating" window that last 30 minutes every damn time you want to run your game just because they want to update the damn client
edit: and one more thing, you know all that "lets play those old games i bought 10 years ago because today games are expensive/crappy" idea, well forget about it because either because ye-old-steam will not work in that time's tech and making emulators for that kind of thing is much much harder (and probably ilegal) and thats it if they actually let you backup the damn thing, as offline cracks/patches get released theyll resort to keeping vital game code online requiring to download it on each play to enforce DRM
edit: and one more thing, you know all that "lets play those old games i bought 10 years ago because today games are expensive/crappy" idea, well forget about it because either because ye-old-steam will not work in that time's tech and making emulators for that kind of thing is much much harder (and probably ilegal) and thats it if they actually let you backup the damn thing, as offline cracks/patches get released theyll resort to keeping vital game code online requiring to download it on each play to enforce DRM