A few points about Paul's offense and it's use by high schools:
One of the posts above quoted a high school coach saying that the offense is too hard to coach. That's not really the case; there isn't a single football offense that takes a genius to figure out. However, most HS coaches didn't come up in the spread option and, as some of you may have noticed, this is, in general, not a band of people who will crack the books to get the O and the coaching straight. The shotgun spread is easier to teach and most of them have some experience in it. So they stick with it. You can't blame them for that.
The second reason was exemplified by the Flowery Branch program. Jaybo ran the TO as a junior, then the team switched. Why? Their BB graduated. The shotgun does not require that hard running midline-buster to be effective. Most shotgun teams don't hit the B gap regularly and a mid-size back with some speed will do just fine. To run the spread option you need a good BB and at least one half decent runner who can fit at AB. Not every team can do that.
Some above have also hit on the rule changes. This is not an unsurmountable obstacle, however. It makes some blocks more difficult, but, as 2014 showed, this isn't a killer. We were steadily moving toward bigger OLs so we could combat the difficulties and Paul didn't seem that concerned – we did lead the nation in rushing last year, after all.
Another post said that the practice requirements were too great. I don't think that's so either. What the O did require (and this is why the academies like it) is discipline. The plays have to be blocked as written, the OLs and skill people need to keep their heads on straight and make the blocks required, and the whole thing depends on disciplined team play. If you get that – and this is why we always did better when we were experienced – the O succeeded. The shotgun, oth, depends on putting superior athletes into a position where they can win one-on-one contests. After the game in 2011, a Clemson fan said that their O was based on letting their athletes make plays, but Paul's was designed to produce specific results for specific plays. Couldn't put it better myself.
None of this means we can't succeed with a shotgun spread. Lots of teams do and there's no reason Tech can't. But if you want to see why the spread option isn't ruling the roost in HS, all you have to do is look at the experience of the coaches. That's the biggest factor, imho.