Just a money market account or something (e.g. https://mercury.com/treasury ).

Also X=Y for almost all startups.

The point is, treasury accounts are not designed to manage crypto. So that's another layer of money management that startups have to deal with, when they could simply ignore it using a treasury account.

But of course, YC being YC will fund another startup which will help other startups manage their stablecoin portfolios...

Also note that in most jurisdictions, you cannot pay employees with crypto, stable coins or not. Nor can you pay suppliers. Or AWS/GCP/Azure.

This is literally a textbook example of, in YC's words, a solution in search of a problem.