The guy who postulated and validated the way that the mitochondrion operates was very much a scientific outsider and had to secure funding and run his lab outside the traditional scientific apparatus.
To be honest I doubt I would have believed him at the time given the context. It's a pretty complicated theory that requires a subtle understanding of biophysics.
Remember the reception to the Avery/McCloud experiment- people still insisted protein was the heritable molecule. People simply couldn't understand how a "simple" polymer like DNA could encode information. it was a real mind-bender because (AFAICT) nobody really appreciated how nonuniform polymers could code for information.
Or the reception to the discovery of enzymatic RNA. How could RNA possibly be enzymatic? Well, now we know that RNA runs the game and protein is just muscle.
https://en.wikipedia.org/wiki/Peter_D._Mitchell