Rarity is a matter of perception — at the time of the Teaching, the population of the world was a hundred times smaller. Oddity can be attested to, but what was once a rarity is now a minority statistic. As much as the population has multiplied, the number of pratyekabuddhas must have risen in tandem: to suggest otherwise would be to assign pratyekabuddhahood to external entities or mechanisms as something bestowed upon someone, but as it is, pratyekabuddhas arise independently — were that not the case, would they still be pratyekabuddhas?