You and I have very different ideas of what "everyone" means. USDT is not even accepted by everyone that deals with crypto, even less if you actually start thinking about the financial institutions that are looking into crypto, and the amount of people who would take USDT is infinitesimally small compared to those that would accept greenbacks in a regular transaction.

USDT is only accepted at shady exchanges that couldn't find a banking partner and their ignorant/SOL users who were forced or "incentivized" into taking USDT for a premium.