Simple: if what you want is to try to get eyeballs on your art, you’re not going to post it on a website that restricts its visibility. I’m never going to see that much content beyond my own instance. I need to follow the artists individually to see their art, or they need to be somehow connected to someone on my instance.
That’s the ultimate non-starter.
Twitter doesn’t have this problem, and Twitter still works (mostly). It’s still the only reliable source for commissions.
Do you understand the difference between owning a forum and running it? u/spez isn’t moderating /r/bioware. This isn’t about who should own these forums, but how they should be run.