Not exactly what you are looking for, but there are a few archives which try to save the deleted questions from StackOverflow (I don't know about the other SE sites). E.g. http://stackoverflow.hewgill.com/

> Why doesn't someone launch a site for such questions?

Occasionally they do. But they take a lot of effort to moderate and generate negligible ad revenue, so they usually do not last long.

Quora?

A practical question about emacs would be on topic on unix.stackexchange.com or superuser.com.