it's always a variety of different actors in any social process like this. it's not any one singular body. but if you want to speak broadly, no the "epidemic" thinking is not widely accepted in psychiatry anymore.

however the idea of modernity bringing new causes that increase the prevalence of certain mental disorders (which seems contrary to OP's claim) is still being explored. either way, whether it's more prevalent now or not, there's no question that autism predates its label. well, beyond the ontological question of "is it really there if it doesn't have a name", which is an admittedly important question.