The thing about the VM is that it apparently has statistical properties in its distribution of glyphs that are somewhat consistent with that of common human written languages, and yet were not known at the time.[0]

It's possible that the VM was intended to be meaningless/undecipherable, but that the writer(s) just happened to have come up with a process that both produced these statistical artefacts and managed to elude cryptographers for centuries, but Occam's razor would similarly say that such a process is not the most likely one to have been chosen/invented.

On the other hand, at the word level, "Voynichese" looks very different from natural languages[1], which suggests there is some deliberate artificial process going on. That could be something like encryption, or the writer(s) inventing their own writing system out of necessity (e.g. they spoke a language that didn't yet have a writing system, or there was some esoteric goal that this new writing system achieved).

[0] https://en.wikipedia.org/wiki/Voynich_manuscript#Statistical...

[1] https://knowablemagazine.org/article/society/2021/can-statis...