I've now read it, and I don't get it. OK, so stablecoins should be Fed regulated, brought into the FDIC network, and prohibited from mixing with commerce. In essence, the stablecoin issuers become like banks in the regulatory sense. Let's put aside whether or not you think that is a good idea and ask a simpler question: what about "all of crypto"? Does that have to be put through the same legal ringer? What does it mean to ban general crypto from affiliating with commerce at the institutional level? To guarantee crypto issues with the FDIC?
You might say this is only for "stablecoins," but does the document give a rigorous legal definition of that term? No. How stable does it have to be, to be a stablecoin? What if there is no stability guarantee, but the issuer acts to create an expectation of relative stability. Is that a stablecoin? Or just crypto? What if the price fluctuates "a bit"?
You may feel "I know a stablecoin when I see one," and maybe you do, but I very much suspect that under these proposed regulations you either kill all of crypto, or hardly anything ends up being legally classified as a stablecoin, though it still might be pretty stable!
What about a "not quite stable coin," but you buy a separate contract with a "separately capitalized" intermediary, so that you are each time made whole, and can de facto treat the value as really quite stable?
Maybe they have clever answers to these questions, and just didn't see fit to include them in a 26-page document. But I am sooner inclined to think that Treasury is not currently handling this issue at a sufficiently high conceptual level.