It's also the most unbiased word for referring to a group in a gender neutral way I've seen lol most others have implications of status (gentlepersons, folks), are still technically gendered (guys, not to mention this implies relatively young people too), or overbroad (everybody is well, everybody. Chat implies you're addressing your community or a small group since they're the ones who would be talking to you).

Brainrot is commonly used as just a general term to refer to later genz or gen alpha humor I think

It's the sort of thing that every generation does to make their sense of humor sound unique and new