Here's the advantage of being easily amused: You're amused a lot more often. Anyway, there's not much to "get," it's a harmless way that people use to signal that they are in and feel part of a community, like the rubber duck thing for Jeep drivers, or Swifties.

Not everybody has to like it, or participate. I would just point out the Frequency Illusion, a.k.a. the red light effect, where it seems a lot more prevalent because you emphatically notice it.