Well first of all, you shouldn't ever look at comments section seriously on Youtube, especially if you're the creator of that video. A better example of bad artistic criticism is something I found a lot with some Fine arts students.
"Oh my God, those proportions just HURT"
"You should always learn your fundamentals first, then create your style. Otherwise don't bother."
" Learning how to draw from anime? LOL"
"There's no excuse to skip on your fundamentals"
I was once just looking for an old drawing of mine, just needed it because it had a concept design I liked. Someone saw it and began giving me a speech on what's wrong with it. I'm thinking, mate, first of all, it's a concept design for the outfit; the "pro-porshuns" don't matter.
Helping someone is not immediately looking for "what's wrong." Especially with such varying styles, and purposes of one artwork (Important),
Uh, I don't know how to write out my thoughts reasonably so I'll just go for your questions.
For me, I don't give a shit if some artist comments on my style. I know what needs work. My goal is to be able to write a thoughtful and well done story, and draw it in a way that appeals to me. When I need improvement? I go to the professionals I know who can give me either a fundamentalist perspective or that pure artistic perspective. I don't trust kids on the internet who can't help but tell you how right they are and how much they think they know.
Tutorials? Honestly, I think tutorials are tough when they try teaching you small bits of an overall study, say for example, figure drawing. They've not really been that helpful for me, at least little youtube videos. You have to put in the practice yourself when it comes to art, which may make tutorials seem unhelpful. In that case, criticism from others is helpful, when you want to improve. But best look for someone who has experience.
Sorry, my thoughts go all over the place