Actually, BigOrange, they do. I'm consistently amazed at how many QUALITY football players the state of Montana produces, year-in and year out. I did a quick look and in the last five years, Montana high schools have produced six all-Big Sky offensive or defensive linemen alone. Not to mention the great Montana kids who have been all-Big Sky running backs, wide receivers, linebackers and defensive backs in recent years.
Sure, Idaho produces some players of that quality, but not nearly as many as Montana. And Boise State, Idaho, Utah State, BYU, Utah, and lately even Weber, all divide up that smaller pool of Idaho players. And, as you point out, even MSU and Montana have recruited some good Idaho players in recent years. (The Dlouhy kid from Idaho Falls, for example, was an all-Big Sky defensive end at Montana -- even though Lewis and his staff worked VERY hard to try to get him to come to Idaho State). Adam Boomer, the LB from American Falls, was also an All-BSC player for Montana. (That one WAS a miss by ISU -- Brian McNeeley didn't think Boomer could play and didn't recruit him).
But when is the last time you heard of a Montana kid that left the state to play for another Big Sky Conference school? I bet you can't name one Montana kid who left the state and became an All-Big Sky performer at another school? Most other Big Sky Conference schools don't even bother to recruit Montana kids because they know they won't leave the state. They have no compunction, however, about raiding Idaho for players.