I think the wide availability of the internet actually made things worse, not better. Before the internet, there was always magazines that dealt with these subjects, pamphlets that people hand printed, books (back when bookstores were a thing). You definitely had to go out of your way to find that stuff, but it was always there. A lot of older technology like numbers stations[4] must have fed into a general feeling of unease with governments as well, they could be tuned into with relatively simple equipment but their use was opaque and well protected.
The following list is by no means exhaustive but offers a few examples of serious, not serious / parody works.
The outright hoaxes meant to spread misinformation seem to be relatively common, easily spread by word of mouth or cheap pamphlets and endemic.
Recent-ish but pre-internet dissemination of wild theories that occasionally sucked people in: The Stranglers made an album about men in black[0], "The Illuminatus! Trilogy"[1] covers a few different conspiracies that were apparently influenced by letters to Playboy.
The Fortean Times[2] started in the 1970s although it seems not all the writing was meant to be taken seriously. Some people did though.
More seriously and much older, The Miscegenation Hoax[3] was an actual conspiracy to discredit Lincoln.
The following list is by no means exhaustive but offers a few examples of serious, not serious / parody works.
The outright hoaxes meant to spread misinformation seem to be relatively common, easily spread by word of mouth or cheap pamphlets and endemic.
Recent-ish but pre-internet dissemination of wild theories that occasionally sucked people in: The Stranglers made an album about men in black[0], "The Illuminatus! Trilogy"[1] covers a few different conspiracies that were apparently influenced by letters to Playboy.
The Fortean Times[2] started in the 1970s although it seems not all the writing was meant to be taken seriously. Some people did though.
More seriously and much older, The Miscegenation Hoax[3] was an actual conspiracy to discredit Lincoln.
[0] https://en.wikipedia.org/wiki/The_Gospel_According_to_the_Me... (1981) [1] https://en.wikipedia.org/wiki/The_Illuminatus!_Trilogy (1975) [2] https://en.wikipedia.org/wiki/Fortean_Times (1973) [3] https://en.wikipedia.org/wiki/Miscegenation_hoax (1864) [4] https://en.wikipedia.org/wiki/Numbers_station (1914-)