I think there are good use-cases for SPAs (Google Maps, for example), but the majority of cases that I've seen aren't good ones, and the extra complexity involv

I think there are good use-cases for SPAs (Google Maps, for example), but the majority of cases that I've seen aren't good ones, and the extra complexity involved in managing state etc. far outweighs any marginal gains in not re-instantiating JS.