I've wondered about that, too, so thanks for raising the question here;;
@Rodimus13 you're giving some good reasons as to why it's bad for us creators when people just sub, but don't read.
Thing is... I often sub to a series so I simply don't forget to come back to it as soon as I've got the time. I've stopped searching for content, though, because I don't have the time nor the mind to read anything new right now. I keep tabs with exactly two comics and try to read two novels as often as I can, but... yeah.
I kinda wonder... Do I need to feel bad for using subbing as some kind of tbr pile? Wouldn't it be better for Tapas then if we had a feature that would serve exactly that purpose – only without adding dead subs? Is that something the team might consider, @michaelson? 
Because, not only would it erase dead subs, but it might ease anxiety over not reading all the time when someone updates EVERY. SINGLE. DAY. Stresses me out to no end when I see the notifs all the time. xD