You can publish traditionally-formatted comics there. But from what I've seen so far on Webtoon, it's difficult for me to read fonts on comics that are in traditional format if I were to read on the mobile version. I'm not sure if it's still the same with their app. But the last time I checked their app, it was the same. Desktop version has no problems for me.
The thing that I love about Tapas is that I can zoom in on traditional-style comics on mobile version which is something that Webtoon doesn't have.