95% of them do.

Further, even if they are integrated with Steam via the Steam API (they literally are shipped with a steamapi.dll), you can usually get around the soft DRM of it using something like the Goldberg Emulators (basically a version of that DLL that doesn’t connect to Steam’s systems).

The problem is that if you care about games having or not DRM, you can’t make an informed purchase decision in Steam because they don’t give you information about that when you’re considering buying a game, so you only find that out after you bought it.

This is even more of a problem that merelly single player games that won’t run offline because some forms of DRM which aren’t phone-home DRM can still make it impossible to run that game with Wine or Proton - I have a game from Steam which won’t at all run in Linux no matter what I do, yet a pirated version of it runs just fine with Wine.