Life was easier when it wasn’t so easy to fake a photo...

Modern conspiracy has nothing to do with facts, but entirely to do with the shape, rate and self forming nature of modern human communication networks.

I'll argue, strongly, that right now - everything regarding Social Media misinformation is an epiphenomena of those factors.

To illustrate -

Misinformation based communication travels differently than "Fact" based information https://www.pnas.org/content/113/3/554.full.

People assign truth value based on heuristics, one of which is how many times information is repeated. If you self select a network of people who believe the same things and repeat it, with slight modifications - you can ensure people will believe conspriacies.

With the ability to self select nodes/people who tend to be conspiracy inclined you will easily cross the number of people needed to make an idea seem socially valid.

The pace and size of our information networks naturally supports the evolution of highly viral content - not truthful content.

When was that, 1880? You can do some pretty funky stuff in the darkroom when you are making your prints.