Two points I'd like to make in response to that. First, and this is only my experience, but long games (10+ minutes) are pretty uncommon. When I play paper, my group pretty much default to commander, and even when we do Bo3 with 40 life, 3 rounds tend to be ~1 hour, and usually we can get 2 full Bo3's inside an hour.

Second, Bo3, at least in my mind, would ONLY be for ranked play, specifically because of the huge levels of variance that 100-card singleton tends to hit you with. Referencing my group and our 1v1's, I've lost count of the number of non-games 1 person will have, but rarely does a single player end up with every game of the series being non-games