But by how much and does it actually matter? It's also a pretty small example. The problem of complexity outstripping benefits only grows the more you inspect the frontend landscape.

My main point is just that the implication that JS is required otherwise the UX will be unbearable is false. It's also really easy to mess up the UX with JS and I see it constantly. I would take a fast form post over a cumbersome JS powered experience any day.