Doesn't that depend on game devs?

I mean, I can copy Baldur's Gate on a PC where there's no Steam at all and play it just fine, because the game itself doesn't have any restrictions. If other games have DRMs I don't think it's Steam fault.

If you want to be totally free from DRMs you need to check GOG, if a game is there, it doesn't have DRM, so neither the Steam version will.