Steam/Steamworks is DRM. You can’t purchase games on Steam and play them independently of Steam.
The overlay, the community pages, reviews, friends chat etc were all there circa 2010 and function identically to how they do today. Regional pricing was there too, today it’s been reneged in many countries to protect against region-spoofing.
The primary group of people who prefer Steam only for Steam Workshop and/or Community Market are those who seek to extract profit from them. There were paid mods before Steam Workshop and it was fine. There were digital collectibles inside games before Steam Community Market and it was fine. There wasn’t any skin gambling, though.
These systems are designed to provide functions which already existed, but with Valve taking a cut of the sales. That is a profit-adding for Valve, and literally value-reducing for consumers. They are popular because they are bundled with a popular pre-existing service, that’s it.
There are plenty of games that are entirely DRM free and can be played straight from the EXE.
Steam Workshop is a massive value add. The premise that it’s not is a joke. Not every game has a community that distributes mods that way, but it’s by far the easiest way to add mods, and the people who value steam for Workshop absolutely have nothing at all to do with extracting profit.
The game studios have an option when publishing the game through them to use their DRM, there are a ton of games that allow you to run it with steam off or even uninstalled from the PC, it’s just a lot of games choose to include the steam drm on it (usually to allow for steam achievements as that is not possible without it to my knowledge), sadly steam does not provide a good way of identifying what games do this and what games don’t. I believe you may be able to check this by checking the games executable in the install location to see if it uses the steam schema