They actually don't list on both usually. Go lookup the data before you start making statements like that. In fact just go punch this into Google: "how much of airbnb inventory is unique?"

I’m basing it on personal experience looking into renting a vacation rental and I have family who list on both. I am not going to google that because I know what is true

That's quite a broad assumption based on anecdotal evidence, you know what's true based on your few experiences renting and from a few listings your immediate family has, how can you even believe it's true based on this flimsy data?

Quick edit: just searched on both VRBO and Airbnb for rentals in my city for the same date range, VRBO shows me 191 options, Airbnb shows 330 options.

That's very anecdotal to your city. VRBO could be renting more than Airbnb. I am not going to go to extreme's to overly analyze this. I made my point.

My point already shows that your whole assumption is flawed, which was entirely my point... You don't need to argue but it'd be in good faith to at least acknowledge that your point has no basis at all, it's just your feeling, not a point.

By the way, I live in a capital city in Europe so the discrepancies between listings would probably translate to many other places...

I already said what you claim I did not say. I will give you the last word but not here to argue about it.