I think there's maybe a couple folks who are readers and just interested in the behind-the-scenes.... but on average, the thing is that readers don't really... need a forum. A forum benefits creators, who want to talk shop and advertise, but if readers want a place to bounce reactions to the recent page off of other people, that's what the comment section is for. There's no need to come into a forum and scream OH MY GOSH DID YOU SEE THAT LATEST PAGE OF BLAH COMIC to a bunch of people who may or may not read Blah Comic, when you can just post your comment on the page itself and yell with other readers there. Forums wouldn't really be able to serve as a fandom space for any comic because there are too many different comics on Tapas.
I'm trying to think of what else readers might need a forum for and not coming up with much. Generally non-comic-related hang-outs are something you can get anywhere on the internet, and sharing recommendations for other comics you like isn't something you'd generally want to join an entire forum in order to do, and would only even be interesting to the sorts of folks who are reading hundreds of comics and always looking for more.
So while the idea of making forums that readers want to join certainly sounds attractive to the creator folks who advertise here, I can't really think of a reason why that would be attractive to an average reader!
