Man, Letsrun really has changed since the early days. Can't remember the last time I saw so much mileage bashing. I'm basically on the OP's side, with the caveat that you can't really prescribe a single number for everyone. But the basic idea is sound. High schoolers should be trying to high mileage, building up higher each year, though not necessarily year 'round. There's not really a reasonable dispute that the mileage makes you faster, both in the short and the long term.
The only question is whether there's to much of an injury risk. The answer to that is fairly simple. There isn't. High mileage isn't inherently risky. In fact, it's safer than high intensity. The main risks of high mileage are: (1) having too sharp of a buildup, and (2) increasing intensity without cutting mileage. The latter is the main issue I see. Guys will put in an awesome summer of mileage, show up to XC in the fall and start doing really hard workouts without cutting their mileage back at all. (Depending on the kind of program, you can keep your mileage higher further into the season if the workouts are mild at first.)
It's true that some college coaches want low mileage guys because it makes them look like gurus to have runners make breakthroughs. I think this is a mistake, for a few reasons.
One problem is that low mileage guys end up injured in college because they're building up volume and intensity at the same time. Even if the coach isn't trying to overtrain guys, the significantly more competitive atmosphere often causes guys to do it to themselves. By contrast, a high school runner who has a high mileage background is far more likely to be able to handle the incrementally increased demands of college running.
Another problem is that a low mileage guy with good high school times is likely to have comparably worse times at 8k and 10k. I'm sure that most of us have seen high school studs running terribly in cross country races because they're so unprepared for real distance. The high mileage guys, by contrast, are much more likely to contribute to cross in their first years. Some coaches may think that they shouldn't need to depend on freshmen for their cross team, but that's not how it works out in the real world. You never know for certain who your team is going to be. You have to play the odds.