Correct me if I am wrong, since I am new to Tapas, yes I think this is a place ruled by numbers so far, I m not sure it is the most effective or a fair way of working, but I do think that the reason why we do not have much space in the Apps for example or pickings is because Novels, so far, do not have an active daily number of views, shares, subs etc...that great for them. So every single sub count for the Novel aspect of Tapas, every link every activity and if that increases a lot well we get to be more noticed as a profitable thing for the owners of the site.
And second:
There would be two aspects of what I said:
1- If you asked for sub and someone did it for you it is nice that you do the same and that is only to support who supported you.
2- If you do not do this, do not post in every thread asking for sub then you decide if you want to support those that supported you, though I would since that is how I am...
And the final aspect:
I think remove someone from the library only because they did not sub you in return will impact the first thing I described. Also for me it is not nice since it will definitely bring some bothering to the one that lost a subber.