Historical ciphers, when they were introduced and their effect

[ReneZ]

Conclusion: all known ciphers that have actually been used before the late 15th century make the plaintext even less like Voynichese than would be the case with simple substitution.

That seems largely correct to me.

Let's also not forget that this text has primarily attracted cryptographers and cryptologists, right from the very start. This is therefore perhaps the most trodden area of all. Unfortunately, we don't seem to have any detailed explanations of all the things that have been studied, and why they failed...