I don't agree, it is finicky, breaks the flow and takes longer time than a real page refresh without javascript. And after a certain depth collapses everything

I don't agree, it is finicky, breaks the flow and takes longer time than a real page refresh without javascript. And after a certain depth collapses everything and you have no idea where you were or how to get back. Even in the perfect world with performant js and no issues the concept still has no merit.