I hadn't heard of this before, but I think I can see how they're getting there. With no punctuation, you have to infer the emotional detail from the context. If you add a period, it can be perceived as specifying that you're using a flatter, less excited tone.
Compare:
Grandma's coming this weekend
Yay
To this:
Grandma's coming this weekend
Yay.
On top of that, these kids are used to using emoticons and such to indicate a variety of emotional shadings, rather than just an exclamation mark - so deliberately specifying the flattest, least interested emotional load could very well read as just waiting for the conversation to be over.
In Narnia, the inhabitants were complaining about the witch making it "always winter, but never Christmas!" And this was before the local Christ- equivalent sacrificed himself.
People keep talking about divided media and a lack of shared shows - did nobody else see all the KPop Demon Hunter outfits last Halloween? I swear it was about 20% of the outfits at my kids' school. Nobody seeing the Stranger Things merch in stores for the new season?
There's still new shows most people see, and some are good ones - but the media landscape changed. Used to be, in the US, you had CBS, NBC, ABC, etc. The difference is now it's Netflix, Disney, Paramount, and so on. The quality mix is still pretty much what it was, but you've got to go to where they've moved to - YouTube doesn't have much professionally done content.
As for 67, that just seems like what memes have always been to me. The Beans meme here was random too, but no less meaningful for it.
In our case, it's a sign that my kids struggle with extra-long noodles. We're letting them get used to scooping with a fork before worrying about much longer strands.
I largely agree, but I don't think people actually need to have an "other" to hate. I suspect it's an easily activated community-level defense mechanism, if that makes sense. One that's easily a used by manipulative people.
I'm just trying to figure it if there's an evolutionarily-selected use for having manipulative power-seeking types in our populations, or if they truly are more analogous to a parasitic mutation of a more conventional personality type.
The sport isn't the problem.