A way to get around that: Personally, I've found that anyone I have a match of >94% on OKC has a high probability of being the aforementioned Rationalists Who Just Don't Know It Yet.

Really? Back when I first joined I wouldn't have been surprised by this, but they've fiddled around with the match algorithms since then, and 94% matches have gone from extremely rare compatibility to fairly trivial (and yes, I've checked against people whose match values I knew from before the algorithm changes to make sure it's not just a result of a larger userbase.) These days, I could browse through a considerable number of people with that match rating before finding anyone I would expect to relate to.