I agree 100% that knowledge for the sake of knowledge is never a bad thing, as long as no one is PHYSICALLY hurt in the process. If new knowledge offends, or hurts feelings, well, too bad so sad.
What, exactly, is being compared? Total rough extracted? Total cut and suitable for setting in jewelry? Would diamonds, corundum and beryl include industrial grades? Would ruby & sapphire rarity include the 10,000+ tons of emery (predominantly corundum) mined annually in Greece and Turkey? How would you factor in the attached 375 gram ruby and kyanite with fuchsite carved Shiva lingam into your relative rarity estimates? Or the attached 21.5kg Madagascar sapphire specimen? Estimates of relative rarity are meaningless as there are no scientific guidelines or criterion for establishing what ultimately wind up being just wild guesses.
As such, these wild guesses are being used as bull$#!+ marketing tools to help dealers and jewelers close sales. Claiming Blue Sapphire = 100x Rarer Than Diamond, Emerald = 200x Rarer Than Diamond and Ruby = 300x Rarer than Diamond is really no different that claiming your emeralds are “old mine”, or “Muzo” color, or your sapphires are “old mine” or “Kashmir” blue. At the end of the day, these are only meaningless marketing memes. But, they sound good when trying to close a sale.