“But if you reject those starting points, the humor is gone.”
I would posit that the humor has merely been displaced elsewhere. Maybe the intended recipient of the humor has now become the butt of the joke.
Nobody was the butt of the jokes, actually, because at that time nobody really believed they were of the opposite sex or were even ravingly gay, but it was a funny image. The humor came from how improbable this was (like Klinger in MASH).
There was no hatred involved in this, btw.
The modern crazies (trans, etc) weren’t really the butt of the jokes either because they didn’t exist as a protected class at that time and barely existed at all until the last couple of years (when they, along with black criminals, seem to have emerged as our most important citizens).
For something to be funny, you have to start from the normal situation. We have ceased to live in a normal world.