[quote=@Bluetommy]
Professional editors generally don't edit someone's prose to fit their own wants. 
[/quote]

Okay, so professional means publishing right? Since nothing else fits the bill for that word. So I'm guess that's the story you're sticking to.

But that's not true at all when it comes to publishing. You will have editor ask you to change characters, events, erase entire lines or paragraphs. Add thousands more words here or there. (Something I do know from a friend's personal experiences.)

There's a minor note in this YouTube video here where someone goes through the processes of what happens when you go through publishing. Where seemingly unnecessary edits were offered akin to "This story takes place in this city, let's change it to this one instead."

[youtube]https://www.youtube.com/watch?v=tuRE55YH8yE[/youtube] 

Good video, and worth watching to anyone passing by.

[quote=@Bluetommy]
Fanfiction is using someone else's creations to tell your own story, it's not at all "rewriting someone else's voice", that's absurd.
[/quote]

To you and to me maybe, sure. But don't think for a second that all authors think the same way. Hence why some get angry and pissed at people writing fanfiction about their works. For reasons that are basically argued as soiling their original property.

[quote=@Bluetommy]
I'm going to let you in on something, when it comes to storytelling? There is no objective quality.
[/quote]

I fundamentally disagree. And that's just wrong. Yes, in the most general sense, the beauty is in the eyes of the beholder. I suppose. But saying all writing is subjective, has and will always be used as a defense for laziness. And it only comes across as a slap in the face to those that put effort into their work to make it as polished as possible.

[quote=@Bluetommy]
The author doesn't have any more obligation to listen to your opinion. 
[/quote]

Sure. Who said they do? But it goes a long way when you don't assume every piece of criticism is personal or bad faith.

[quote=@Bluetommy]
Many pieces of fiction are better because the creator didn't listen to criticism that didn't match their vision. Tvtropes has an entire page of this.
[/quote]

Cherrypicking. And honestly, the reverse is not only true. Frankly there's many, many more examples in T.V, movies and games in recent memory, where fan reactions/concerns have been proven entirely correct.  

[quote=@Bluetommy]
If you present those criticisms in an impolite way, say completely rewriting their work in your own style without their permission.
[/quote]

Good thing that's usually never done, eh? Since, most of that advice is solicited to begin with. Whether to whom is made to read it, or where it gets posted. (Context matters after all.)

Or to erase the already razor thin border of subtly, it's also far more likely that this "failure of permission" was a post in a writing contest where anyone with sense, would expect their writing would (and I argue should) get thoroughly evaluated and critiqued. Take critique how you want.

I'll ask you the same question, since you clearly accidentally left it out.

Why is "your sentences are complicated and vague" more helpful and acceptable to say, than "Your sentences complicated and vague, so if you don't mind, let me provide you potential solutions as to precisely what I'm talking about." 

In both cases, the person giving said advice, is asking the author to change their original work. Likely to make the author's sentences more clear and concise. So assuming both people are doing that in good faith. Where one often gives no examples and provides no solutions. And the other does so. Is the first better because...they put less work into their giving their advice? Is it nicer to leave an author clueless on what the former even wanted? Simply because it there's the chance it will hurt one's feelings a little less, from the sheer lack of context for them to dwell on?

Again. All ears.