Imo Steam should tell people whether or not a game actually requires Steam (or another form of DRM) to run. I know they already do it for things like Denuvo, but they should also note if the game actually uses Steam as DRM or if the game can be launched without it.
Steam DRM isn't even really DRM in the traditional sense and it's very easy to put games into a program or use an injected/patched .dll to bypass the Steam Launch check. It's annoying sure but it's not something that people should be concerned about.
Steam sells DRM-free games too, you can download them and then uninstall Steam and they will work. In this case though, on top of purchasing the game, you are buying a license to download updates for it through Steam. It's a developer decision.
For example, you don't have right of resale the same way you would with physical goods. You're buying a license to the game for personal use, regardless, you just don't have DRM limiting your access.
Well that's just digital goods, not Steam specifically.
You do get all the files for the game, that will work for as long as the OS will run them, with or without Steam (this is as close as you can come to ownership for software). Rather than a license to use them files, which become useless if you don't run the game through Steam.