Crowbar, the fact that 'old' is in your name would suggest that you remember, or even participated in the so-called running boom. Maybe not. If you did, I can't think you'd find my point (which is that just because your school district hires a coach you don't have to be coached by him/her) bizarre at all.
My personal experiences, along with those of the 3 guys I ran with the most, might not mean much. We were certainly not worthy of appearing on the cover of any magazines. However, by running road races - a 20 mile in early November (wouldn't that conflict with XC season) or a marathon in March (wouldn't that conflict with track?) or various 10ks during the school year - we noticed a lot of kids our age competing against us.
Who cares? Well, it shows that non-school-affiliated training and racing is not only possible but was common among teenagers as recently as the '80s. Whoever won my age group at the 20 ( it must have been pretty near 2 hours flat since I did 2:11 and wasn't top 3) definitely didn't run a cross race the day before, the road race in question being on a Sunday. These kids were probably not part of any school team. I'm being vague and using 'probably' because we didn't know them if they were from another school or district. These days you'd stand out and the kids would know each other if they were on the local road circuit, but there were a dozen good ones at every race, it wasn't considered remarkable, and they didn't know me either.
Again, why is this relevant to anything? 2 reasons: it worked then; and it can be done now? Being self-coached really did work in the '70s and '80s. The top pros were not all part of well-established groups like BTC or up-and-coming groups like Saucony Freedom. Herb Lindsay was (as far as I knew, correct me if you know otherwise) self-coached; Shorter was self-coached after Yale (which is to say, the whole time he was good) as was Bacheler. These guys, including Rodgers, who wasn't coached by Squires after Squires signed with NB, were not my generation but they were just before it. They were our role models. Just a little older than me were Virgin and Salazar. According to Al's autobiography he was with Dillinger for a while but on his own for most of his prime.
You say it ends badly and that is occasionally true. I included Salazar to be objective, although a Comrade's course record is not a terrible fate or embarrassing last race. Ryan Hall wasn't anywhere near the runner he ended up being when he was formally coached by a school. Keep in mind for Hall that such was only the case at Stanford, where his performances were unremarkable, as his High School didn't have a coach and he started running on his own. Lukas V was not coached by his school nor were Fisher or Cain (nor Efraimson, I believe) at her prime. So the lone road warrior isn't just a thing of the past; it happens still.
You may point out that some of the above did end in a train wreck. At least all were good at some point. How many kids with the combination of terrible school coaching and lack of vision to go without it don't ever get good? How many of these stories end badly. A 4 year stint of 16th placing in bush-league meets never to run a step afterward. The kids coming to the MB to complain about the school's coach (and there were several on this thread alone, not to mention the threads they start daily) crash and burn without ever even tasting their potential success. Is this your preferred outcome? How many of these unhappy kids could go under 33 for 10km? Modestly talented though I was, there are a lot of 17yo on the board that couldn't have beaten me at 15. I'm not saying Salazar at 25, but the thoroughly unimpressive me at 15. Some of them are never going under 3 in a marathon no matter what. But if I could do it during my first year of HS I have to think a lot of them are being held back by the very coaches they come here to complain about.