It's because it's the lowest common denominator of referential humour, and no one bothers to set up any sort of context for the joke itself, effectively killing it.
People are getting stupider and no longer have to rely on their own imagination to come up with "Funny" jokes.
Also, it's a culture thing. Most of the time, it's us who've made the joke in the first place. It was ours, and we had a good laugh for a while, but then we start seeing it everywhere and it's just not funny.
For example, let's say you and your friend go on a road trip
and on that trip you make a joke that only you and him could ever possibly truly understand because of where you were and what you were doing
It's fun to reference it every once in a while because you remember the original context of the joke and why it was so funny
But then your other retard friend overhears you
and he thinks it's funny, but doesn't bother to ask about the context
then he starts using it a lot, and other people use it too, until no one knows the original context
Your friend has effectively killed the humour for your and taken away an experience that previously only you and your bro shared
And that's just apples man.
TL;DR They bastardize what was once ours. We only care because we were emotionally attached to these jokes