Earlier quoted context omitted.
Not everyone has or wants Steam. I'd rather deal with NexusMods than with Valve as a GOG user.
This ain't a defense of Steam Workshop - it has a lot of issues and sucks quite bad- just a remark for anyone struggling with using Workshop next to anything else. You don't actually need a steam account or the client - with SteamCMD you can have CLI access to all the mods there, as well as download any mod (or, for example, dedicated server hosted via Steam) to a custom location. As for what's bad with Steam Worksho…
Not 100% correct, some are restricted to accounts that have licenses for the game. Same with some dedicated servers, you'll get an error ("Failed to install app "xxxxxx" (No subscription)" ) if you try downloading anonymously