I have said this before but like a lot of others point out, Tapastic is filled with more creator rather than reader, and creators have their stuffs to do, hence why they can't be as active as reader in checking out new comic. Combine that with the fact Webtoon usually has 5 times or more visits than Tapastic daily and you can do the simple math.
Also another factor is the way Discover section on webtoon works compare to the Fresh section Tapastic offers. On Webtoon, often than not you get complaint for posting one page daily, people rather you combine all of them together and give them a long update. It's why new comic being posted to Webtoon has higher chance of staying on the front page of the new section compare to Tapastic which has 823902321 comics update almost every minutes around the clock.
Beside that, Webtoon's discover offers a lot more visibility for comics be it small or large. They have weekly hot, popular by genres along with a recommended titles that changes up pretty frequently with different series no matter how big or small.
They also have a visible side bar with top popular comics that changes up every week. I know people will complain "only the big subs count comic will make it on there!" but that's only half the truth. Comic only stay on the list for 1 week no more, and after that if you haven't updated a new episode, you are off the list. Same thing happens when you are on the list but you update a new episode, you will immediately get taken off of the list because the list keep count of the amount of active view/comment on your latest update. This give new series a ton of visibility chance to pop up on the list, and even a few hours is a lot to draw in new readers! (That, combines with the fact people on Webtoon are more likely to update weekly or biweekly :D)
Personally speaking, I'm more scared of posting on Tapastic, maybe it's just because I'm heavily under the impression this is a creator's ground, and creators are always a lot more judgmental when it comes to series that they would take a liking to, unlike on Webtoon which is more of a reader place. Anyone can take a liking to your series just because they like your art, your premise, or some of the most silly stuff. (With that said because they are readers, they fail to understand a creator's pain, so some of them might come out a entitled, that is understandable.)