I personally know a Youtaite who is around 33 years old! There are a few indeed who are in their 20s so ye ur not alone, it's just that a majority are teens
Hello! Youtaites are still very much alive, although only a few rank among the more well known side like Aruvn, JubyPhonic, Rachie, etc
Newer Youtaites tend to be quite young and can often be found in Youtaite Discord servers. They also have a Twitter community and currently, in Youtaite land, the new "thing" right now is chorus battles where people get together to make choruses and they tend to be super high quality!
Please keep in mind that the English VOCALOID fandom is lesser known than JP fandom, as this is evident by not a lot of English producers are well known vs Japanese producers.
I hope this helped!