Isn't the whole thing conceptually the same as or very close to a money market fund then (absent the specific regulations there)? What is the advantage?
I mean conceptually this is just VUSXX (with a lower interest rate probably), but you can buy something online with it through a PayPal checkout page, or send it to a friend through the PayPal app, or send it across borders in seconds. I do think that has value from an ease-of-use standpoint.