I think there's a consensus going for breeding bees for varroa sensitive hygiene/ mite resistance, but treatment free is excessive. You don't need to let the colony die when you're concerned with selecting for genetics. Just eliminate the drones and remove the queen next season.

I mean, you can always withhold treatment until mite counts indicate a problem. Letting mite populations explode can impact other colonies(domesticated & feral) in the area as well.