What I mean is basically that you might have assumed that by banning racists and sexists and transphobes you'd end up with a community of people who are nice to be around. This did indeed cut down on people using slurs and making specific arguments or expressing specific political viewpoints that are outside of what we classified as acceptable (say, "gender critical" stuff for example). But it didn't have to the knock on effect of making the place or the people actually nice. It prevents it from being intolerable in specific ways. It made it "not awful" but that isn't the same as good.
Ultimately, the community was and is still full of people who are mean to each other (and external groups), overly argumentative, combative, and often very toxic. They're just toxic in ways that aren't explicitly banned. People who were abrasive assholes online 15 years ago are still the same abrasive assholes now, they just don't make gay jokes anymore. In retrospect this shouldn't have been surprising, but it still saddens me. I think we did it better than a lot of places online, but it still feels like a failure that we could never "solve" this.
I think this is an interesting perspective.
Being a bit older I remember growing up without forums, so I always put it down to what I call the "pub test". That is back in the day if you said something stupid you were generally in a public place like a pub. If you got punched in the face, you probably didn't say that thing again, or you watched your mouth.
It was a decent system. You could always avoid that place after, but especially if you didn't live in a big city you'd run out of places fast or worry about running into the same people. For internet forums or games? You can just create another account, or server, or go from gamefaqs to steam forums or resetera and do much the same thing. There are no consequences and no accountability.
Which creates two massive problems. Firstly people are massive dicks, as you mentioned perhaps in "Acceptable" ways. I for example might be quite toxic towards organised religion, but know how to mostly not step over the line.
But even worse, I think it has led to a culture where people have been dicks for so long, that they are absolutely terrified of consequences being introduced. If you have spent 10 years being an asshole, how bad would it be if you were suddenly found out and it came into your real life? Pretty damn bad, so people fight hard against it, get sucked into right wing extremism and "culture wars" all because they didn't get punched in the face early on like they should have.
I also don't know what the answer is. Perhaps some sort of parenting with actual awareness of what kids are doing online. Perhaps this will happen with a future generation and fix itself, perhaps not.
But yes, steam forums have always been like this. It is why it amuses me when people claim a new gaming platform like epic or ps5 or whatever needs "community/social" features. Maybe one day that would be a good idea, but maybe give it 15 years and we can try again.