Utah and Idaho. Kids who are members in Idaho who would want to cheer for BSU would take important pieces of BYU's fan base. Think about it. BYU was at it's peak before Utah and Boise were big players. There weren't many houses coaches went into that they didn't have a great chance to come away with the recruit. Dividing your territory is not a good idea. Utah-Idaho isn't Texas. There aren't enough people/talent to go around. And yes, you can recruit anywhere, but you should always have a leg up in your region. It is hard enough to split local talent with Utah and other P4 teams. Imagine a relevant BSU to contend with... it makes it that much harder.