I've had enough experience with 10-person teams trying to synchronize code for a large UI to think otherwise.
Trying to do that with "just HTML, CSS & JS" either dooms the project or ends up with the team implementing their own flavor of React (or something else) to standardized complicated state update in a modular fashion that allows sharing code.
Not everyone needs React, but when you do, it's nice not to have to reinvent the wheel.
Facebook is one. So is Google Cloud's dashboard. Basically anything where a single UI will be serving multiple separable concerns (that could be handed to multiple separate teams in a large org).
Trying to do that with "just HTML, CSS & JS" either dooms the project or ends up with the team implementing their own flavor of React (or something else) to standardized complicated state update in a modular fashion that allows sharing code.
Not everyone needs React, but when you do, it's nice not to have to reinvent the wheel.