Oh for sure the "haute cuisine" production (haha I like the term) seems like a tough choice for newcomers specially in the webcomic world. But I'd say, it'll depends on how you go about it, building an audience while you are working on your comic seems the logical thing to do, specially if you are new.
If you post character design, concept art or any kind of teaser of your project consistently, that kind of content do pick the interest. And they are bound to be excited when the comic is finally online.
The "already-established" comes from years of teasing the project, from what I've seen. (I'm talking purely about comic artist, not illustrator who transition to making comic)
On top of my head, there is 2 artists that I follow and I saw their audience growing as they were teasing their comics.
Koteri.Ink and Project Divider.
The first one recently took pre-order of the first volume. He was working on it since 2017 and finished it in January of this year. Looking back at his instagram, he talks about the project in 2016. His audience wasn't at 200K in 2016 but it grews this big because he kept teasing his world.
Project Divider followed the same pattern and he will drop the comic soon on Webtoons. And it will probably gather a good amount of attention.
Using comic to establish your identity as an artist from the start, it's definitely hard because even if it's free, people consume as a product, in most case they are not curious about the behind the scene, about the artist, if they don't like it, they move on.
It can be cold. A concept art feels different, it's you, practicing. People aren't as critical.
When you are new, there is no rush of publishing your comic right away. No real benefit (imo)
There is no pressure of trying to stay consistent or relevant.
You put the right amount of care, cut corners where it needs to etc.
The use of assets really stem from the need of keeping the weekly mark, specially if you don't have any buffer.
It becomes a necessity more than a creative decision. And that's when it gets tricky for me.
But that's the part of the business.
I definitely understand why artists would use those tools tho'.