Oh my god, yes this is hitting the nail on the head in a way I hadn't thought before. The bloat comes from the discipline (or lack of) more than the framework.

IMO, those who have only worked in React tend to be unfamiliar with the layers of native capability that React is built upon, and so they are stuck in the React bubble unless they want to learn a ton of (admittedly crufty, but useful) web fundamentals.