Actually the Regional qualifying process is telling you that. If they have won 31 titles then they have been dominant for longer than there has been a Kinney/FL XC Championships.
If they haven't (and Delaware hasn't) produced a single qualifier in all that time then it is NOT BECAUSE the deck is stacked against them, it is simply because they never had anyone good enough.
I live in Michigan and our local paper had a front of the sports page feature on Maverick Darling (ended up 10th). He goes to a VERY small school with very little running history or tradition. He had a brother few years ago who was very good, but otherwise the school records would likely be 2:00+, 4:30+, 9:50+. This is a farming community that is VERY rural and nobody is rich there. When you drive into town they have a HUGE statue of a cow, 8-10 feet tall. Think milk and corn country ...
Anyway, why is someone like him able to win 3 state titles and qualify for FL, and go on to a 10th place finish?
Because he can run 15:20-30 on a legitimate course. If you can do that you will qualify for FL. If you are in a tough regional, you may not. But that is the way it goes.