The article to which I linked lists a few stereotypes that seem clearly true to me, and any reasonable person would readily act on them. (Would you really get equally scared of old ladies and young men when walking in a bad neighborhood?) So how exactly does your common sense alone let you sort out true stereotypes from false ones, and to conclude that most stereotypes (by whatever measure) fall into the latter category?
Moreover, if you believe that acting on some kinds of stereotypes is unethical, that's a defensible position which I'm not going to dispute in this discussion. However, this position leads to the awful problem of what to do when some stereotypes are at the same time unethical and accurate -- and a common attempt to get out of this problem is to argue that all these unethical stereotypes must be inaccurate, which you seem to be doing. But this is clearly wishful thinking; reality is never aligned so conveniently with abstract moral theories.
There was a historical shift in beliefs.
I find this very odd. How could a major cultural lineage be wrong about something so much a part of ordinary experience?
When I say wrong, I don't necessarily mean that we're right, or the ancients were right, though there's a lot of evidence that the Victorians were wrong.
My favorite theory is that people's amount of desire for sex varies sufficiently that there's enough noise to make it easy to see patterns that aren't there. I leave the possibility open that there was a change (possibly dietary) which affected libido levels differently between men and women.
People are sufficiently punitive about sex that there's going to be lies and misdirection to support the current theory about how people are supposed to be.