For the same reason you'd laugh at the fauxpas of that goofy nerd kid in class.
Is it really difficult to understand that this was cringe before the word cringe existed?
I guess if you watch 10 hours of cringe shit these days it became the norm and people are expected to behave that way.
Back then, it wasn't. It was something that wasn't supposed to be seen by a multitude of other people. Like America's most funny home videos. Or Fail compilations.