We've all seen this artist before: their execution of a particular piece could use some improvement, so we try to give them some pointers on how to improve their art for the next time, but then we get the response:
"Well, that is just my artstyle!"
Let's just put this person's words in another context: that's like saying "bad technique" is its own musical genre, which just sounds absurd. An artstyle is not a valid excuse for bad technique. I think an easy way to tell whether or not it is an artstyle or whether it is a lack of technique is the intention of the artist.
Let's say that I set out to draw the human figure from reference. If I fail the execution and the neck looks a bit too long, or the space between the legs is a bit too big, can you say that that it is indicative of "artstyle"? Well no, because what was the original intention? To create an accurate drawing of the human figure, so this would be an indicator of bad technique. Of course, it sucks to have not drawn it accurately with proper anatomy and proportions, but that can be fixed. Bad technique can be fixed, but using "artstyle" as an excuse for bad technique makes it seem unfixable. Why? Because artstyle is part of the individual and their approach to art, not of their mechanical ability.
I see this all of the time: person creates an original character with human features, but the execution is less than stellar to put in better terms. The technique could be improved, most definitely, and that should give hope. But instead they tack on the excuse of "it's my artstyle!" to cover up the fact of a messy execution. Well, if your artstyle is like that, I'm afraid that it can't be fixed. Why? Because if it is an artstyle then it must be intentional, and if something is intentionally bad then there's no hope in fixing it, because the artist themselves sees no reason to fix it.
Of course, I've made some intentionally bad art in the past to give me and my friends a good laugh, but is that what we want to be known as artists? I sure don't. And if I intend to create a human figure I don't intentionally botch all of the anatomy. Some people do so intentionally, but more often than not it is for different reasons (for comedic effect, as an example). In that particular case, then yes, it is an artstyle, as they had intended it to be that way, rather than it just coming out scuffed on complete accident.
It is clear that an aspiring artist does not intend to create sloppy artwork, which means that using artstyle as an excuse for falling short is quite sad, and also very dangerous way to think. Have you seen those artists who have been drawing for years, even decades, and yet not a single thing improved in their art? That is what this type of thinking can potentially lead to. If your bad technique is now your "artstyle", then everything that you create will have semblance of bad technique. But since it is an "artstyle" and not an issue of bad technique, then you would not see a reason to correct it, right? And if you see no reason to correct it, then you'll never improve. That to me is a scary thought.
So please don't use artstyle as an excuse. It will harm your growth as an artist.