How many updates did these series do, again?
Because I have less than 20k subs on Webtoon and got nearly 500k views in August. In my case, the reason was that I did 8 updates.
This month I've done 14 updates on Webtoon so far. Generally I use frequent updates to gain subs faster and to remind people that my patreon exists (I feel that patreon exposure is more important to me than the quick extra few hundred bucks I could gain if I optimized my updates to fit the webtoon pledge program, since that program will end sooner or later but the patrons and subs are more likely to stay). It is possible that some of the creators you guys are suspicious of are using the same methods?
Talking about genuine updates here btw, not reuploads to cheat the system.
If these people have slow updates, no previous audience, low quality art and low quality writing then it's very likely that they are using bots.
If their art and/or story are good, it's possible Webtoon was just their lucky site. Or they have another comic on this site or some other that you haven't considered, and they have an audience there.