I coach a girls high school team. We've been to NXN/NTN once. We've won several state championships. I can still count on one hand the girls in our program who've run over 40 mpw at any point during the year. And, frankly, our top seven would crush many NCAA DI programs and a substantial majority of DII programs at 5K.
We're on a long-term project of raising mileage, but we're raising it slowly. Results are looking good so far, but taking a 25 mpw kid to 45 mpw in one year is just begging for trouble. Look at the number of wrecks that have been made from taking extremely talented high school girls and pushing the mileage big time in college. You know the names. If you don't, you shouldn't be opining on this thread.
Plus, someone else has made the point that you have to have at least five healthy or none of it matters--at least from the team perspective. Preferably, you'd have at least seven both competitive and healthy. But, whether you put the number at five or seven, you find there are very few top teams in the country that aren't racing on a razor-thin margin. I'm not willing to crank the mileage total at the expense of an enhanced injury count; I don't have the bodies to fill in. Winning is a lot more fun than stress fractures.
Finally, it takes a special kind of person (male or female) to love the experience of HS XC at 100 mpw. There are lots of very talented runners who'd never do it if the expectation were anywhere near that high. Some will, of course, and there's something admirable about that. There's also something admirable about making an 18-something runner out of girl on 35 mpw and having her love the experience. She can decide when she goes to college if she wants to go 70 or 80 mpw.