I believe one thing are promotion threads and another thing "promotion" threads.
People sharing in promotion threads related to the art of a series, latest chapter, latest sentence, and other dynamics that don't actually require for the meaningless sub x sub activity are ok. After all people are having actual conversations or just simply promoting they are being active regarding their comic. Sub x Sub is meaningless because it's not often someone will read your comic because they liked it, is phantom subscriber, it's there but does nothing important.
There are other threads as well which are not in the promotion Category and still allow promotion, it cost nothing to select said category or to scroll down a bit more to find them, as well, if conversation is what some are looking for, I believe the discord Server is ideal for that as well, since everything is separated in categories and the only place you get to promote something is in the promotion channel, so I believe in there you'll find a more satisfying experience and to talk about diverse themes with other people, as well for advice, asset recommendation, tips and other things.