Ironically, the thing that supposedly no one does (setting innerHTML) in many cases is still much faster than using the finer grained DOM APIs the way React or Svelte would.
I think it's hard to argue that these frameworks are out-of-the box faster than using the DOM APIs directly. What they do is provide abstractions that lets you scale HTML-interactivity up much faster.
Plain-JS DOM manipulation code can become quite complex very fast, and I think that's what opens the door for inefficiency and also a lot of errors, because it's hard to keep track of possible DOM permutations.
