Yes. Everything is conjecture. Unless we are in their heads, we will never know, and even then, they might be lying. So let's drop the obvious and get down to what matters and what it says: actions.
The ACTIONS of Webtoons betray what they are thinking and planning.
You would think that they are ultimately thinking of making money. However, if they were thinking that they would allow the audience to dictate what succeeds and doesn't, but they clearly squash everything they decide not to promote within discovery. They would promote creators that provide massive content with some kind of minor popularity, but stuff like Bite-sized (now Probl-o-matic) never gets any hand.
So clearly money isn't "all consuming" and there is agenda > money.
Prolific titles will bring in good revenue once their "ad revenue" program begins. I have no idea what that ad revenue program will be like, but I hope it is 2 ads/page with .1 cent per ad, 50-50% webtoons/creator. That might be much too hopeful.
But money is a high priority, and this contest (back to the contest!) is aimed solely toward helping the ad revenue program following behind. Webtoons has a problem: it is the king of the hill in western webtoons at the moment. It could be easily toppled, if they don't secure the next step properly and a wealthy competitor steps in.
The contest is almost certainly rigged, heavily slanted to the ultimate winner, at best. They are already promoting a bunch of comics and letting the others rot. I still don't see the entries on my desktop platform. I finally saw them on my iPad this morning, and they are a long list in no particular order that is helpful to discovering hidden gems. You can choose rigged or incompetence, I say rigged--top of the heap is already a comic they hawked in the square for many months.
However, what the contest is doing (I hope they meant to do this) is getting everyone rabid for a carrot. So ALL WEB COMICS CONGREGATE ON WEBTOONS. They will become a central library of almost everything out there that is kind of current or even archival. Very smart. And then they will transition into ad revenue to keep people there.
The contest is just a foothold to the next, necessary, phase of being the king of webcomics.
But I doubt there is any altruistic motive from Webtoons.
As for purity of motive on the artists' behalf, they are flooding in there for the money. If a comic artist is only doing it for the cash or hope of cash, they are blowing it; become a stock broker! Lawyer! Dentist! The contest should be seen as a tourist trap off the side of your life's highway.
"If they didn't make you, they can't break you" If you hinged your career on Webtoons' revenue, Webtoons will break you like a dry twig when they take away that revenue. Make it elsewhere and the Webtoons trough doesn't mean so much, because you are your own person.