Fandoms exist because when you have no real direction in life, you tend to grasp at the the easiest things available to you so that you can be attached to something.
So if you have to reach for 'the easiest thing available' to be 'attached to something', this means:
1) You don't have a pet
2) You don't have a lover
3) You aren't married
4) You don't even have friends
5) If you fit any of the above, you don't actually like/love them
Or in short you're like the biggest nerd who spends all his time in his mother's basement, doesn't even get visited by his mother anymore and therefore has to be attached to his last resort, a fandom. And since fandoms can grow to millions of people, that means we have millions of millions of people spread out in different fandoms who have nothing to love or be attached to. Right?
And because of mob mentality, the notion is extenuated and validated by the large amount of like minded people also looking for something to attach themselves to.
Thus said basement dwellers convince other basement dwellers over the internet that fandoms are the way to go.
Liking something that you can defend as being good is all well and fine, but when you devalue that content by constantly drawing attention to it is where you become a problem.
This paragraph has nothing to do the one above. Just because people with 'no real direction in life' attach themselves to a fandom, does that mean they constantly advertise their favorite work around? Why aren't there people wearing sandwich boards to show how much they love a particular show, without even working for the show?
I love
Ace Attorney but I don't go around shouting
OBJECTION!!!, do I? Chances are the only reason you know I love
Ace Attorney is because I explicitly mentioned it right now.