Zipf’s law states that in natural languages, a word’s rank order is inversely proportional to its frequency in a corpus.
The main issue (aside from the ones mentioned) is that many things that aren’t languages also follow a Zipf-like distribution.
If the Voynich manuscript had just been a list of every bird the writer saw out the window, the word frequency would probably follow a power law too (there are lots of common birds, and fewer rare ones). This is the defining quality of Zipf’s law—it fits so many things.
The main issue (aside from the ones mentioned) is that many things that aren’t languages also follow a Zipf-like distribution.
If the Voynich manuscript had just been a list of every bird the writer saw out the window, the word frequency would probably follow a power law too (there are lots of common birds, and fewer rare ones). This is the defining quality of Zipf’s law—it fits so many things.