While I wasn’t a mod for Steam proper, I was a mod for a popular game that routinely had its share of hate groups and 8ch mobs try to take over. The flagging system worked pretty well for keeping the worst of this stuff out. Plus, the publisher is permitted to make moderators for its own Steam forum. So if you are seeing shit get out of hand on a particular title, blame the publisher, not Steam.

Paying someone to do that kind of work is the opposite of Valve's ideal, if I understand them correctly.

They prefer systems working well enough with as little human assistance as possible—see: review system with reactions and surge detection; user-defined game tags; front page recommendations completely based on trends; the market; and so on.

That's not to say these are bad, but they could often be improved, if only Valve was willing to pay the human cost. But part of the reason Valve remains small is they try to automate as much as they can (and if it can't be automated, it might never get done, specially considering their corporate structure).

N.B. I still prefer them over majority of companies in this space, but let's not ignore their issues, e.g. gambling. As an aside, I also appreciate GOG's "no DRM" stance, but I use Linux and sadly native support isn't there. Kudos also to Itch.io.