The crackpots had a greater barrier to transmit back in the day. They had to get an FCC license or know someone with a radio station. Even then reach was limited unless you could reach a deal to transmit nationwide.
I personally believe our brains are primed on some level to buy into this stuff. It’s very hard to overcome.
> When you’re young, you look at television and think, There’s a conspiracy. The networks have conspired to dumb us down. But when you get a little older, you realize that’s not true. The networks are in business to give people exactly what they want. That’s a far more depressing thought. Conspiracy is optimistic! You can shoot the bastards! We can have a revolution! But the networks are really in business to give people what they want. It’s the truth.