We don't! But, we don't really have any good ones yet. And even if they are good it takes time for them to prove their functionality and ability to resist market stresses. You can't do that with just a whitepaper or even a few months of market testing. USDT is just an example of a shitty stablecoin that is successful because it was early. I cheer for all the better stablecoins to replace USDT and their shady operations.