I don't have an agenda to disprove IP. I want to live in a universe where it works, but so far it really seems like we don't. I hate to raise the spectre of UFC because I know you guys hate that. But millions of dollars, multiple careers and issues of national pride rest on the outcomes of those matches. And sorry, but they ARE the best comparative test of martial arts we have available. They scrape for every microscopic advantage they can gain. They generally deride IP and that's the most credible opinion I know of.
IP of compelling quality is extremely rare, but it is there. It's just not fair to say "we don't" live in a universe with it based on data points collected by an individual, because there are other data points that indicate it is there.
Dan Harden, for example, typically characterizes himself as an MMAist first and foremost (and reportedly still trains MMAists). I know an MMAist who's been a wrestler since high school and currently trains at BJ Penn's UFC Gym here who put Dan Harden in a mount (there were multiple MMAists at this particular venue, and so katate- and ryote-dori stuff wasn't their bag so much). Dan placed the palm of his hand against this MMAist's flank, and demonstrated issuing spiraling power from flat on his back (basically a no-inch palm-heel strike) that popped this seasoned fighter two feet in the air, horizontally laid out, and cleanly off to the side. The fighter on the receiving end stated, upon gathering himself and taking a quick inventory of his ribs, "this is beyond anything taught in the fight game."
So if IP is that effective in MMA applications, then why isn't it the training protocol of choice among elite fighters in the UFC and elsewhere? Well, why would it be popular in the UFC if its dissemination via methodologies conducive to imparting it to a broad, primarily western audience is still slowly gaining traction within the traditional arts from which the methodologies were derived (UFC 1 occurred well before the interest in what Dan, Mike Sigman, the Aunkai, ILC, etc. are collectively doing began to hit critical mass, so the current IP movement is still quite young)? If traditional martial artists who are looking for aiki and other forms of internal power are slow adopters as a whole, then how much less buy-in can we expect from those who, as you indicate, thumb their noses at it (personally, from those I've spoken to, it's simply not a concept they're aware of)? And, there's always a cost-benefit equilibrium point, especially when cost-benefit is literally about money, for individual fighters and the sanctioning body. Who wants to tune in to The Ultimate Fighter
and see a bunch of guys doing standing-stake and torifune for the entire season of episodes?? Dan will be the first to say that developing IP and learning to fight are largely mutually exclusive endeavors. Each individually will take several years, and then there are the years needed to effectively meld those skills. Maybe if someone's rare and preternaturally adept at both and doesn't have to hold down a day job, they get there in a decade. For a young fighter looking for or in need of a payday, or simply seeking to scratch the competitive itch, it makes sense to default to proven external training methodologies that bring him/her up to a competitive level ASAP.
Nonetheless, the data points will come, Bill -- at least in pockets within the traditional arts. There are enough contemporaries who are studious, disciplined and mission-oriented doing the work for that not to be the case during the next few years.