I agree. Frankly, a lot of the "low mileage" HS coach advocates are old school coaches who don't continue to learn and just do what they did back in the late 80s and 90s and then wonder why they don't have great teams, just a few good individuals (the ones with a ton of talent who can get away with a low mileage approach). I do know several 'low mileage' coaches who do an amazing job with their teams, but these guys are still actively learning, networking, teaching other coaches, etc. and have legitimate, well thought out reasons for being low mileage programs (like the only surfaces they have to run on are concrete!)
Even better than having a one-size -fits-all approach, whether it's low mileage or high mileage, is having a somewhat individualized approach based on the runner, their abilities, their preferences, how injury prone they are.
I just want to laugh every time I hear about the 'upside' of a talented low mileage kid going off to run in college. How often do those kids successfully transition to a higher mileage college program? Sometimes it works out, but many of those kids don't make the transition either due to injury, or due to the higher time commitment required to train at the college level. If your 30 mpw high school program didn't do any supplemental strength work (which is astonishingly common), how long can practice last? 45 minutes? An hour? Quite a shock to go off to practice in college and realize you are going to spend hours each day training. Not every college coach is willing to change their training 'system' for these kids- they just hope the kid eventually can handle their training. I try to get our kids to a mileage level that will make their transition to college running a bit easier.
Having said that, I have had plenty of kids who can't handle mileage, so we modify their training and help them become the best they can be on lower mileage. Some of them are pretty good at the state level. But most of our better boys are able to build mileage over their HS career to the point where the boys can handle 60-65, even 70 miles per week or more by their senior year. Our best girls have been able to run 50-55, with a couple hitting 60 mpw for part of the season. For some of these kids, if we had stayed at 35-40 miles per week, they'd be OK but probably not running what they do by senior year, since many are kids with little speed, modest natural ability, who need the volume to be good.