Blood will Flow

I can see where they're coming from but "Write what you know" is such terrible advice. If we held to that there'd be no sci-fi or historicals or any stories that weren't about writers sitting in a room navel gazing.
I think this is a push back from too many people writing about other cultures and not bothering to fact check. Sensitivity readers are so important. It's easy to attribute behaviors or history to a different culture that we've learned through the media, that just aren't true, or to erase parts of their history altogether in an effort to be respectful that just ends up being insulting.
It's too easy for inexperienced writers to slip into writing stereotypes. We've all done it...coz writing is hard. But to say no one should ever write outside of their own experience is just daft.