Traditional banking services are hostile to crypto, so they cut off Tether's ability to trade in USD. And Tethers own interest (widespread use of USDT) is at odds with their inability to provide adequate backing USD. Exchanges all wanted more USDT to provide more liquidity, and so Tether just printed USDT without backing.
A crypto backed 1:1 by USD is a great idea, the trick is finding a way to actually guarantee the backing currency & exchange rate.