Also, just my perspective, but I think this set-up is the best balance of function, cost, and versatility for most people who want to do both road and gravel/cx.

Get a bike with good tire clearance, get two complete, interchangeable wheel/tire/cassette set-ups, and for the VAST majority of people, the frame of a good gravel or cx bike is not going to negativly affect your road performance vs a similarly priced road bike, not enough to matter.