That is, completely and irrevocably true. From little tweets like "Every time a white writer writes a racist, I go hmmm...." with a GIF of a black woman drinking tea, to flat out "They can't write a Nazi unless they are a Nazi!" bullshit, this shit pollutes comics, tabletop RPG's, literature, screenwriting, and yes, even video games.
Ever wonder why your heroes are over-powered unrelatable caricatures and the antagonists are flatly written (or worse, in the right), it's because of three things...
These people have no actual life experience. They've never gone out and done anything. In the old days a writer usually went out and did shit. Went to war, got in bar fights, was a rodeo clown, drove an ambulance, got married and had kids and a messy divorce, drank themselves stupid and woke up with a suitcase full of guns and money. You know, lived life. Actors were the same way (Jimmy Stewart killed the shit out of some Nazis), so were comic book writers (the old legends did all kinds of shit), and the same with musicians (The Doors, Jimi Hendricks, all those people had a past) and poets.
Now, your "celebrated authors/writers/screenwriters/comic creators" do the "middle class upbrinding/college/job" shit, with a few dicking around on Tumblr for a few years before getting noticed.
So, because they have no experience, everything they create has this weird hollow feeling. Ever notice in modern novels everything takes place in a flat gray space, with no hint about the background, the terrain, any of that? Ever notice the backgrounds for the protagonists all bleed together? To be honest, a LOT of them don't have any imagination. That's why they take over established works, and the things they do create are often lifeless and boring caricatures.
Because of this, most of them can't imagine someone being able to write a racist without being a racist, writing a vile villain without believing as the villain does.
Because they themselves believe everythign the hero believes. The hero isn't a protagonist in the story, the hero is THEM, just inserted into the book to show everyone how right their chosen philosophy is. They have a checklist, from the 3 or 4 chapter story arc to the checklist of characters to the list of acceptable and unacceptable traits for characters.
You see it the most with: "Unless the protagonist perfectly emulates the reader, how can the reader identify with the protagonist" bullshit.
Holy shit, this is getting long, so I'll sum it up...
SJW tards fuck up fictional works because they have no life experience beyond their keyboard and their own social circle. They don't expose themselves to other ideas.
Which is why people like Mark Waid freak the fuck out whenever they can't control and shut down anyone they don't agree with.
They are right, and the other person is WRONG.