I have long felt the killer feature of QUIC is its ability to encapsulate _both_ reliable in-order delivery and unreliable datagram delivery in the same opaque-to-middleboxes container. Whereas HTTP becoming the everything-protocol is debatable, if QUIC becomes the everything-protocol we will be a lot better off. QUIC is the middlebox and censorship killer. Unfortunately that last point is its greatest weakness: censors can currently get away with blocking it.
That and devices are increasingly becoming hostile toward their owners, so you want the ability to inspect and filter traffic from one you can trust.
In these days, its good to have every extra layer to protect yourself. QUIC comes in handy here.
While it does seem that HTTP is the everything-protocol, in the case of MOQ it doesn't HAVE to be involved at all tbh. One can do straight raw moqt:// no http/s needed. Right now and probably for the near future HTTP is the on-ramp and easy to use means to get connected.