Dude, no. Read their replies again and see that they're seriously trying to help you make your offer more interesting for the interested collaborators.
If you just look around the forum, you'll see a lot of offer like yours that didn't get any reply at all (though I dunno about pm).
We didn't know about you and we don't know what you want to make, what your genre of interest, the style you're looking, your writing skills, etc.
Basically, we don't know what are you looking for. You simply just type "I WANNA ARTIST TO MAKE WEBTOON" but we don't know what we're getting into with such little info.
Next time, do it like the examples they've been giving you, and do answer them politely. If you're looking for unpaid collab and partnership, it is going to be harder, since you know, making comic ain't easy and you'll need some resource, something to show that you're capable and commited to do this and good communication to get one interested in collaboration with you.
Also, Lia showing examples of their art and comic link so you could see that they're indeed a capable artist. Plus it is okay to do these "promotion" in this kind of condition, imho, they're not hijacking, and you're being too aggressive. Please read the replies carefully again. I'm not trying to debate with you but they're more, and far more experienced than you on this matter, so give them some respect and learn form your mistake.
(please do excuse my grammar. Peace, dude. ^^ )