I wonder, is this a thing that really bothers people in real life? I've only ever heard it spoken about in online (and generally American) spaces. I suppose it could be a thing in universities, but I kind of think that's expected as they are places where generally young people are learning to develop their thinking and it makes sense that not all their arguments are properly constructed yet. But I can't imagine someone telling another person off for "cultural appropriation" in every day life. Not if they were sane at least. This comes across like one of those issues designed to stir people up, but with no good outcome for anyone. Either you get pissed off because people are "appropriating" and you want them to stop, or you get pissed off because it's another crazy "woke" idea. None of it helps improve society, but I suppose it's easier to focus on this than doing things that will actually make a difference. Why work for years against racism when you can just tell a white person to stop braiding their hair? (which, ugh, is ridiculous. My ancestors are Irish and Scandinavian and braiding and dreadlocks have been part of those cultures for centuries.)
I don't think it'll ever be able to go too far because humans have been adopting each others' cultures since forever. Nothing really belongs to anyone, and if you go into people's DNA we're all a mix of everything anyway. To implement cultural appropriation rules is either going to involve looking at people and deciding based on their looks what they are allowed to do or not; or, because you can't always tell someone's background from their looks, you will have to go by DNA. Either option seems very sinister to me. The people who argue that people shouldn't appropriate other cultures, if they got their way, would end up with a horribly segregated (and unworkable) society, which I'm sure is not what they are after.
I consider myself a cosmopolitan. Everything - art, music, food - becomes more lively, interesting and awesome when we mix together as far as I'm concerned. I've participated in a lot of things considered part of other people's cultures, and the people from those groups only ever respond positively. People LIKE sharing their cultures with others and they like it when others are excited about it. I'm reminded of that girl, mentioned above, who went to her prom in a Chinese style dress. People from China loved it, it was just certain Americans who got upset. And by the way, that is a great example of how things can't be restricted to one culture, as the style of dress she wore was a form that arose in the 1920s, inspired by a mixture of traditional Chinese dress with western styles (more form-fitting than the traditional dress).
It just seems ridiculous to me. Anyone remember that professor, Randa Jarrar, who was in trouble awhile ago for making happy tweets about Barbara Bush's death? Well, she wrote an article a few years ago called "Why I Can't Stand White Belly Dancers", and it is such a badly researched article. She doesn't understand the first thing about the history of belly dancing; it's just a platform for her to work out her rage issues based on her own past. And worse, when people responded with proper research and historical perspective to show she was wrong, she just wrote another article, titled "Why I Still Can't Stand Belly Dancers" in which she didn't engage with any of these serious responses, instead she created strawmen and made childish, sarcastic responses. And Roxane Gay who curated the articles got in on it, tweeting sarcastic things like: "I truly had no idea belly dancing was so important to white people". You think, aren't these people supposed to be academics, and they can't even engage with opposing points of view?