This was all pre-internet, so there was no easy way to research into a rumor or perception like this. Yoko broke up the beatles. Proof? It is known. I don't think younger people truly appreciate how indifferent most people really felt about stuff like this, as they didn't care enough to dispute a claim they had minimal interest in. It's not like they were going to google an old forum post on a whim and try to verify this shit.

It's not even that people were inherently more indifferent back then, it's more that this was all before the internet made it a social norm to have a real take on literally everything. They didn't make a hobby out of hoarding fun facts to post in the comment sections of social media. They had rumors and gossip, but it cannot even compare to the scale and speed of such things on social media.