How many people use Pornhub for discovery though? I usually find interesting content through a search engine, through word of mouth, through posts on here, etc. at which point it doesn’t really matter where the porn is hosted. A lot of the useful content I use aren’t even on Pornhub.
Seriously though, I agree with you, githubs value to open source is not it’s discover-ability. Personally I think its value comes from the stability, as much as I’m an advocate for self-hosting I know from the amount of dead links on the internet that we could have lost a lot of projects or at least they would move about as hosts went down.
I quite like the idea of federated gitea, although technically there is already a federated platform for porn if you count Lemmy and/or mastadon.