The momentum of self-care has been moving away from the reasonable ideas you suggest and toward a cynical, capitalist way to make money. It is a relative of “treat yourself!”

When someone talks about “self care” these days they are more likely to mean “spend a premium price for a treatment at a fancy spa” rather than “eat popcorn for dinner while hanging out on your couch in ratty sweatpants.”

Self care is also sometimes trending toward an excuse to shut out everyone else and your responsibilities as a human being, because you know, self comes first.