Is Steam horrible? As far as I know you can log in as another account and download games the other account has and play them, and if you log back into your acco

Is Steam horrible? As far as I know you can log in as another account and download games the other account has and play them, and if you log back into your account the game data doesn't go anywhere (so if you buy you don't have to redownload) but you can't launch them from the steam client. Why didn't Apple do something similar?