I've only seen a little Bluey. It's a good show, but it's very much a show for and about preschoolers, and I just don't gravitate towards cartoons that skew quite that young, so I haven't felt the drive to watch more. I definitely see something in what I did watch, though. The show is creative, the adult characters are funny and well-written for an older audience to relate to, and it feels like a lot more thought and care was put into it than other preschool shows. You can tell the people working on Bluey wanted to push the genre forward in meaningful ways. I get why people enjoy it.
I'm not 100% sure on the timeline here and this isn't something I've researched, but based purely on vibes I get the feeling that the Bluey zeitgeist was amped up by the pandemic. I think a lot of parents were stuck at home watching more TV with their little kids in 2020, and Bluey just stood out to them as a show that's much better than fuckin' Paw Patrol or whatever. It's just a cute and relatable and funny little show about a family. And from there I think a lot of childless adults heard it was good from these parents who watched it with their kids, and thus latched onto it as a comfort show during these last few horrible years.
This is VERY different from MLP:FiM's rise to prominence. While MLP certainly had parents watching with their kids, and also returning fans from previous generations (mostly women), the capital B Brony Fandom was born specifically because 4channers caught wind of a scathing review from Cartoon Brew calling the show, and The Hub as a whole, "The End of the Creator-Driven Era in TV Animation." A thread on /co/ made fun of the article's alarmist tone, and then some of them were like "lol what if we checked out the silly pony show that's supposedly killing animation. but like ironically tho," and then they realized it was actually a good cartoon. Because of this, while the fondness for the show was largely sincere, there was always an element of irony to the way the older male fandom talked about it. "lol, isn't it funny how I, a [teenage boy/adult man], am watching a doll cartoon for little girls?" "lol, isn't it funny how mad the people on other boards get when you post pony memes and say 'howdy everypony' and tell them to watch the show?" "lol, isn't it funny when we say we 'watch it for the plot'? wink wink nudge nudge?" By comparison, discussions around Bluey are much more wholeheartedly sincere, less driven by meme culture and more focusing on it being a cute comfort show.
(Of course, the thing no one seems to want to admit with either show is that a lot of the most ardent fans are just autistic. You can say the same thing about most fandoms, honestly, though here it does add an undertone of ableism to some of the "ugh what's with these cringey weird adults who watch kids' cartoons" complaints.)
As for the way people talk about adult fans of Bluey as Completely Changing The World (for better or worse), I think thinkpiece writers just have a tendency to overstate how much stuff they see on Twitter is representative of some seismic cultural shift, be it positive or negative. So many thinkpieces are just "this group of people who've been annoying me online lately is what's ruining modern society," whether it's Bluey Adults or Bernie voters who are rude to NYT writers in their mentions or whatever, and it usually feels overblown. Like, it's easy to look at the wave of adults posting about Bluey and go "oh my god, the new generations are infantilizing themselves, they want to watch this toddler cartoon instead of challenging fiction for adults," but like... I just don't think that's true at all? Like, my boyfriend watched a bunch of Bluey as a form of escapism during a period when his anxiety was flaring up a year or two ago. He is also a person who would say his favorite manga ever is Oyasumi Punpun. People are complex! More complex than can be fully conveyed via social media posts about how they watched a cartoon.
