Liking Kanto has nothing to do with age. Just because the original 151 were released in the 90s does not mean that you have had played Pokemon in the 90s in order to feel nostalgia for them. There are plenty of kids who's first experience with Pokemon could have been Fire Red or Leaf Green, or even Let's Go Pikachu and Eevee, and they would have the exact same attachment to Kanto as someone who started with Red and Blue would. Not to mention that Kanto Pokemon are spread throughout every generation so even if you only played Platinum you're still going to remember Geodude, Machop, Magikarp and Zubat just as much as you remember Bidoof and Starly.

That's why it's stupid when people try to insinuate that only "boomers" like Kanto and "zoomers" only like the new gen stuff when that's not how it works. There are probably more fans of Charizard on this earth right now who are under the age of 20 than there are who are over.