That upside is a real downside as it most always means nobody’s talking to anybody else, the right hand not knowing what the left hand is doing.
It provides little to nothing that normal isolation and normal code can’t do, if people would just take the time to learn HTML, learn CSS, learn JavaScript, and learn separation of concerns with isolation practices.
But apparently that’s asking too much of ^C^V “developers” who get SUCKERED by idiocy like frameworks before they have firm enough a grasp of the underlying languages to even recognize they’re being bamboozled.
Though I will admit that’s less of an issue with server-side code than the client side. It really is client-side where ALL of these frameworks — be it JavaScript or HTML/CSS — piss on everything from so on-high you’d think the almighty just got back from a kegger.