What is it about some internet communities that band together to do something? Is it perhaps for the lulz? In this case, it reminds me of some group projects I had to work with these other guys in junior high. If we had some project to do, it would turn into a large production. It was often imagination running wild, mostly for the laughs of the idea, since we couldn't actually do them.
But here, I guess is not only imagination rampant, but people can do something about it. So as a form of oneupsmanship, they start putting up screenshots, mockups, which stirs the imagination of others to join in on the oneupsmanship.
And perhaps it's because it's so ridiculous that people realize it could never be done elsewhere, so it might as well be done here. Because no one's going to be losing their job over Dudebro. And like snakes on a plane, it just seems like something that should exist.
If someone has a clue, enlighten me. Because as far as I can tell, the most HN's been able to produce has been co-founder dating sites.