It’s basically the same argument that drove XC mtn bikes to 29" wheels as the fastest option.
The introduction of the Pathfinder Pro in 47 is what makes this really relevant with the current gravel bikes. IF the Pathfinder Pro 47 turns out to be faster than the 42, then frames like the MOG that can accomondate 47/700 are going to have an advantage.
In my case, on a Checkpoint SLR, I’d have to drop to a 650b to run the Pathfinder Pro in 47. So any gains in performance for the 47 might be offset by the drop in performance of the smaller wheelset. Tricky puzzle to solve.
I’m hoping the data that comes out of the work Silca and Dylan Johnson are doing testing different set ups at least provides some answers. If you follow what Dylan has been thinking and saying over the past year, such as on the Bonk Bros podcast, he’s pretty convinced that the gravel riders have be running tires smaller than optimal.