The people behind the Escapist are as mainstream as you can get. This is of course a generalization - Russ Pitts falls into this category much more than the Extra Credits crew - because being a game designer, even if obediently holding opinions that are in line with the Game Industry Philosophy Of the Week, is not mainstream in itself.
The community is mostly mainstream. Again, this is a generalization, but it should come as a surprise to nobody. The Escapist is designed to attract as many people as possible and is focused around a very broad and mainstream topic itself - gaming.
More elitist places on the web would be SomethingAwful, bay12 (makers of Dwarf Fortess) forums or the glittering gems of hatred at No Mutants Allowed.
Not that mainstream is something negative while elitist is positive, in and my itself.