It seriously depends on the context of the situation. I come from a background where in online art communities I was a part of, feedback was in fact, common and critique was always a given if you were to post your artwork to begin with.
@Prismisho I think I can better elaborate what @Cerbskies is saying and why I agree with him on that one for that reason so, forgive the length of the post but I do have my thoughts on this.
No one knew each other, but there was a mindset where everyone would help improve with each other. It didn't matter if someone was asking for it or if it was unsolicited, you could either take it or not, but if you didn't you always had the option to deny it with some level of grace instead of acting like an asshole about it. (<- Take note of this part)
However in terms of actually "Fixing" art is adding another layer of complexity to it that I think should be discussed.
The thing is, I would say that it's not constructive feedback if you just said something sucked without elaborating why. That should be self explanatory. So, why does that matter when we're talking about fixing art?
The thing is if you're asking for someone's thoughts or are looking for serious critique while its being made or if something can be done to seriously improve it, then it's not a bad thing for the artwork to get fixed. In fact, if someone decides to give their interpretation of what you are trying to go for then you can at the very least take it and build off of that if you have the desire to improve your skills overall OR if you are seriously struggling with a piece and you aren't sure where to go with it.
However, the problem here as we're talking about "fixing" art because some SJW wants to try to make things their own way and then come off like they're doing the artist a favor when it's already complete. On that end I do not think that is okay because you're essentially trying to tell people that you know better when art is a subjective thing and, in that case those people can go fuck themselves.
That doesn't mean however that telling people how they should go about giving feedback is the right thing to do either. That's just stooping to the same level of the person who is criticizing you is, if not lower. If anything that's just inviting unnecessary drama that you don't want.
All you have to do is say:
"I appreciate your feedback, I may keep that in mind for future pieces but I have no intent of continuing this piece." or in the case where someone "fixes" your work "Your interpretation of my artwork is nice, you have your version, I have mine, and I may consider your advice in future pieces." something to that effect where you're not writing off the person.
Not hard to do that at all.
No one is saying that you have to take everyone's advice on how to improve something or how you should go about making artwork.
I've been on both ends of the situation where someone has given me feedback unnecessarily, or where I have given feedback unnecessarily. At the end of the day when one person starts acting like an entitled asshole then more people are sure to get involved to instigate a flame war.
Grace matters.