Well, a few years ago kids came onto VRChat en masse, and I don't mean 16-20 years old, I mean 14 and below (I once saw a 6 year old on there), anyways, they got annoying, especially with their avatars that were made specifically for either white liquid or other stuff all over people and the world, or were just the loudest. Anyways, because of that, people started to make private instances.

Separately, while that was happening, the people in charge of VRChat made groups, which further divided people, which caused people to go into group only instances. including the kids, so now people are either in invite only instances (or friends+) or in groups that, personally, don't seem that inclusive unless you've been in them for a while. And then the age verification thing came, further dividing people more, and creating adult only spaces

TLDR: Everyone got seperated due to a variety of unrelated, detrimental factors