You can say the same thing about what happened 200-300 years ago. The thing is major events tend to have a lot of remnants left behind, nobody is going to pretend the American Civil war didn’t happen. The specifics of any given battle quickly get murky, and lesser events only have so many witnesses.

Degrees of verification are a thing. LBJ being the US president isn’t in doubt. My family story where a relative was studying at the white house (with his daughter) and he came in and told them not to have so many lights in is jumping through a bunch of hops before it gets to you so you should only put so much weight on it. And that’s history in a nutshell.