To answer the question truthfully, lol, I would imagine it’s because Central is in the middle of everything. It sounds dumb, but what better starting point, right?
The two coasts are hotbeds for all kinds of companies, the biggest cities in the U.S., etc., so I’m not surprised to see those used as a reference when so many are in them.
The Mountain Time area just... kind of exists.
Btw, this might be the strangest complaint I’ve ever read on Gaf.