It is sort of amazing that this subject keeps bouncing from "this did it" to "ridiculous" back to "this did it", and yet the correlation of either a meteorite or a comet impact is undeniable from a data perspective. The platinum theory may indeed be correct but there is a much larger body of evidence that says the comet theory is a better fit. Same results in the end, but also fits into the "cataclysm" stories present in almost every major culture around the world.