I tried sub-for-sub a little, but was disappointed by the fact, that these people seemingly didn't read my stuff. They liked it only after I liked pages from their work (in the best case, sometimes they just never did it) and commented only after I commented (it the best case, again). And these comments didn't look like comments of people, who really read, anyway.
So I saw only the pursuit of numbers in all of it. But if I would pursue just numbers, without caring about safety from ban or about creating real readership base, I would just use the army of bots, because they are much more effective in such cheating.
(Sorry)
I mean, if people do mechanical subs, likes, comments, views... how they are better than bots? They are just less efficient, because they do it more slowly than automaton, that's all. In essence, human readers are better than bots only when (if) they are really reading and make you happy this way.
You can say, that cheating the numbers gives you a visibility, which will lead for gaining more real subs... but nah, it's not that easy either, if your content doesn't "fit in". I saw a lot of cases, when comics, which don't "fit", gained visibility on the main page by being picked from stuff, and yet, they didn't gain many real subs from it.