Not exactly quacks, but like

Ok Aristotle was one of the early guys to be like "wow we should start to figure out stars and shit"

That was great, but his particular conclusions were not great, like the sun orbits the Earth. It was a good first crack at it.

Same with Freud. "Wow let's figure out people's brain and shit, now that we know it's not devil spirits. Maybe everyone wants to fuck his mom"

And of course we all know it was their dad all along