I'm not sure about tapastic, but other webhosting websites tend to have those 'wtf why...?' series that would do mysteriously well and have oddly high numbers. (not super popular, just had oddly high wtf numbers and you couldn't figure out how they got them)
I remember years ago (again this was years ago, the comic is most likely dead and didn't make it over 5 pages) there was one on smackjeeves that was drawn very badly (not anything to do with style, it was beginner tier art the 'Chris Hart taught me everything I know, I discovered the line tool i will use it to draw the VERY long legs, eyes are different sizes, hide the hands behind the back because they are hard to draw, fill bucket everything on the same layer with really bright colours that clash with one another tier art), had dialogue written in MS paint that was almost impossible to read, 2 pages (a title page and an intro page that only said 'yaoi manga this comic has gay sex, do not read if you are homophone') had a description that read '18+ erotic shota comic master and slave' and had around 300+ something subscribers.
At that point your half laughing half scratching your head like ".... how am I REALLY doing worse than this? Really what the hell am I doing wrong?" Regardless of how confusing the numbers where, as well as the fact it beginner tier and bad as the comic was, I can't really say that no effort was put into that on the artists part. The artist was just incredibly inexperienced at art and likely was drawn by someone very young (even though it's an 18+ comic, which is honestly not uncommon online cause even horrible 18+ fanfics are written by kids under 14), and it's very likely that they indeed put all their effort into that work.
That being said, there's not really a genuinely low effort 'super popular' series that I've seen. Maybe 'are those numbers real?' or 'wtf reallly??' but not 'super popular' tier. Sure there are series with simplistic style choices and very noticeable art short cuts, and a heck of a lot of average series that do better than average because they're using a well selling gimmic 'like throwing copy write characters in for a joke' or genre 'and these exist everywhere not just in the webcomic world, take romance for novels and superhero comics for American comics' but even just throwing these things into your series isn't going to make it an automatic sell, and who are you to say that what that artist is personally capable of creating is 'low effort' what may equal low effort to you could equal high effort to them.
As frustrating it is to see a comic genre or style type do better than your own (BL and Gag-a-days in concern to tapastic come to mind here, it's honestly what I see getting complained about the most by artists from this site when it comes to the 'super popular doing well just because it's _____' raging) it's not specifically the comics or the comic creators fault that it fits in or caters to the market readers are looking for. Nor is it a low effort on the artists behalf issue (as subjective as one's opinion on that mater might be) It's just the reader market and demand.