Why is there no more Voynichese in any other manuscript?

[Koen G]

What we can say for sure is that whatever 'Voynichese' is, it never gained enough traction to become common knowledge. Neither at the time the VM was created, nor was something even remotely similar re-invented in the following centuries.

This is probably correct, unless it is one of those things that was so common that nobody bothered writing about it. There are many things we just don't know about the past because they were just things you did. Maybe it was something like a common word game among students, usually played on blackboards or wax tablets or whatnot. None of it survived because it wasn't codex material. And nobody wrote about it because why would you?

Again, I don't necessarily think that this is true, but it's fun to think about. Maybe if a 15th century student saw the VM, he'd ask "Jesus, why did they use all this parchment for playing Frumpfelstumpfel?"