“I banned self-promotion... almost every Community I'm in has a self-promotion channel and in my opinion they're completely useless no one actually goes to look at it unless you're just going there to self-promote and then you never really look at it again”

Ban the self-promotion channel — every community has one and nobody uses it

Self-promotion channels in communities are dead weight — endless link drops nobody reads. Replace them with one canonical place for the member's introduction (with links allowed) and an explicit rule: no "vote me on Product Hunt" / "read my blog" posts elsewhere. The signal:noise ratio of the community improves immediately, and helpful behavior (real answers to real questions) is what gets noticed instead.