Indeed, it is possible to simply take older skins - e.g., from animals that died between 1404 and 1438 - and then write on them, thus creating the illusion that the text, itself, is likewise old.
However, its earliest securely known owner was an associate of Holy Roman Emperor Rudolf II, who lived from 1552 to 1612, which leaves more than a century of ownership missing.
That, however, would seem to corroborate its antiquity.
Regards,
For the purposes of this thread, this article is adequate. Not scholarly, but, good for discussion.
While it would be a tertiary source, it does have a good bibliography.
The section on the Hoax is down the page a bit:
https://en.wikipedia.org/wiki/Voynich_manuscript#cite_note-Zandbergen-origin-of-ms-8