Oho.. what a sensitive topic that I need to stop my drawing time to comment on.
This, I agree. I never knew there's a sub for sub between artists before joining Tapas forum.
As a new creator, What I do when I see this? yup, just follow it. I totally think this is how Tapas work. 
Of course, before reading this thread, I never know there's a similar thread ranting about sub for sub.
I think for a senior artist who doesn't like this better to talk to the forum admin.
Since @orbitkatart here just speaks his/her mind and not trying to put down any artist., I, who already did this sub for sub is not feeling down and I hope other artists (especially new like me) who did the same, not feeling down too. I'm sure all newbie just like me, we just follow the seniors, right?
Oh, btw, it's happened too, twice, some seniors, use newbie like me, telling subs for subs, then they unsub after got the sub. How about that?
Next, I see someone said about validation, even I automatically follow this sub for sub thread, I never once think this is validation or trying to lie to myself. I already know this is not a real reader, so I never hope they read my comic after sub nor I celebrate with the numbers or say thank you card for the sub. Is a deal anyway.
I already know, before posting, this gonna be hard( find reader), and I think my real follower is who visits my blog. I don't know about others, but what I always checked first, it's not Tapas/webtoon, but blog.
I believe everyone's goal, in the end, to see the possibility for monetization. Tapas limit to do this is lower than webtoon, so I can understand for people doing this. Make a comic is a labor, so, who doesn't want to get a little bit of a return?
Thus, until now, not change yet, I view Tapas as a platform to connect with other artists, not to sell the comic yet, since I know better than anyone, I still need many things to learn. I still do, learning, and I think making comics is a great practice for an artist, I see my art take a shape during this period of time.
I understand the stress for you who do this for a living or professional, or spend money to make it, but don't make mistakes, even though I'm still learning, my effort is not a joke either. I literally draw every day until morning, I started to eat in front of the computer, never have time to watch tv/movie/Netflix anymore. I only watched random artists' videos on how to draw this, how to draw that. Probably many of you do that.
Conclusions:
I don't mind sub for sub, because:
I saw Tapas as an artist hub (Just be real, no one true reader for me here).
"wow, so many artists here, but I will forget them, no button to add friends." Easy, sub for sub. 
Of course, you can always, add each other SosMed for an alternative. I am not really SosMed person, I barely open my Fb account, and I only started making other SosMed specifically because I started a comic.
Educated me that art is very broad.
Just a few months ago I was only a reader, and my rule to pick the comic, art looking good then story.
I don't even try to click a comic with the art that not up to my style. I bet most people do this. Even with good art when I found the story boring, I will just stop reading it. I think this is a fact that everybody knows.
But, with 'sub for sub', it's educated me to give changes equally to comic/novel before judging it. I trying to read everyone's comic that I sub, and surprisingly I even found a story that I curious about, even the art not my style.
note: I promised to give it a try not promised to always read it.
related number 2, with sub for sub, I indirectly insist people read my comic first, then I can see how much who keep reading. It's like a survey. I like it if they give comments, critic or feedback too, since I have no one to do this in the real-life, I need this at least online. This way, I know which part the reader notices my mistakes.
Disclaimer: This is my state of mind for now. 'Mind' is a very fickle one, so I might change my mind on one or two my statements here in the future, I don't know. I think there's no shame in that. That's a very human thing. 
So folks, I just stopped by to share my 2 cents and now off to draw. 