These are not universals. I’ve seen the no-shampoo meme repeatedly in online comments. As someone with long, fine hair, I’ve made two attempts to go without, waiting almost a month for my scalp to “reset”. It always looked extremely greasy (like Gary Oldman’s character in Slow Horses).
I have had luck opting for gentler shampoos and not using them every wash, but I wouldn’t speak for anyone else. There is large variance in peoples’ bodies.