But is it honest reciprocity? You can see the time stamps on people's subs/likes/comments--if someone subbed and liked three chapters all in the same minute, what are the chances they actually read anything? It strikes me as dishonest, but perhaps you're right, and I'm reading into it too much. Maybe the person doing it assumes the creator they're DMing to ask for sub4sub knows sincere reading/engagement is not expected in this transaction.
I don't think it's wrong to look for reciprocity at all. I've made a lot of friends on this site from reading and commenting on stories written by people who were reading and commenting on mine. I've certainly commented on stories I admired, hoping that the author would want to read mine, too! But I think there's a difference between putting in that effort to build the basis for a reciprocal relationship and... spoofing engagement, I guess, for lack of a better way to phrase it.
And I get we all have limited time. You can't read every novel and comic on Tapas. You can't honestly engage with everyone who drops you a like. It's worth considering that maybe the people DMing asking for sub4sub aren't expecting you to be fooled by the sub/likes but just to appreciate your numbers going up enough that you'll make their numbers go up, too. But what's really the point of the numbers going up if they don't reflect people actually enjoying the things you've created?
Well, I guess I have my answer to that part, anyway, and it's that there's a tournament going on right now that's encouraging people to get their numbers up by any means necessary. So, that's understandable.