[throwaway09432]

Ok, so when registering on a new site you don't mind waiting back to hear from the server after clicking submit, to find out your passwords don't match, or don't meet the required policy? That's fine. But the majority of impatient and perhaps spoilt users do. In fact I hear people these days complain violently about the most trivial UX issues on websites they visit. User's expectations are sky high.

Regarding the massive nestings of divs. Well this is computer generated HTML. It is ugly as hell, but browsers are well geared up to deal with it, it doesn't create any serious performance issues unless taken to stupid levels. The other side of the coin, with this rather ugly generated HTML, is you get a human benefit, a time saving efficiency. You can spin up a web page with React/Bootstrap in a fraction of the time it took you in the 1990s.