But Shakespeare wrote mostly blank verse, and rhyming is not as much of a constraint on vocabulary in French due to the high commonality of word endings. If it's true that works for the stage tend to use fewer words, it might be because dialogue dominates; I imagine narrative, which consists more of description, naturally draws on a bigger vocabulary than even very stylized dialogue.
Since I'm a french canadian who is lucky enough to speak the two languages, I find it difficult to believe.
Remember that rap (rhyme and poetry) was popularized by poor english speaking people.
I wonder what you would accept as "empirical evidence" of the relative ease of rhyming in different languages. The demand strikes me as typifying one of the obnoxious impulses of the Hacker News community (another of them on display elsewhere in this thread) to dress up a vapid criticism as scientific skepticism.
You could, I suppose, try to do a combinatorial analysis of the ease of rhyming by writing a program to find rhyming pairs in a phonetic dictionary; just make sure your blog post about the results properly acknowledges the shortcomings of your analysis in its title.
0. https://books.google.com/books?id=ByVoAgAAQBAJ&lpg=PA60&ots=...
You didn't read it because I just read it and while the first sentence would make it appear to back your point, it doesn't. First because he doesn't compare french to english but merely explain how the main accent is put on the suffix of words and that, in turn, makes it easy in french to build rhyme.
And if you continue to the next page, he explains how french rhyme are not on the same level as their english counterpart "because most English rhymes involve the root rather than the inflectional ending or suffix [...]"
Bottom line, you are wrong, and you try to pass as knowledgeable. You are a fraud.
Even if so, I find the conclusion unexpected, as Shakespeare not only had a wide popularity in his day, but also coined many new words into the English language.
Also, the ones you mentioned lived in the 16th century, when languages were not very sophisticated.
The vocabularies might be bigger or smaller compared to today. Certainly no one was saying "bae" back then (for instance), but no one calls each other "thou" today, either.
EDIT: except for the older generations of Geordies, apparently.