Before insinuating that the problem doesn't exist, I would have appreciated if you performed a Google Search on various permutations of "does airbnb limit number of properties in wish list". You will immediately turn up a list, for example, of Reddit postings on this topic. If you then search Reddit (or any of the other 100+ message boards mentioning AirBNB) you will quickly see that this is an issue people run into every day. I feel bad for your hosts, in particular, because they get screwed when theirs is the 51st property or beyond added to a wish list because you simply discard it without warning the user. You will also see there is all sorts of misinformation out there, some of it perpetuated directly by AirBNB (for example, "delete your cookies and the problem will go away") which isn't true.
Then, I would suggest reading "Managing wishlists - Airbnb Help Center" which provides guidance for guests on adding properties to a wishlist but neglects to mention that their efforts beyond 50 properties will be wasted.
You will also notice that the ONLY mention on the internet of the 50 property limit is the one I've now posted broadly. It comes up first in most searches on this topic. I've already received over 200 responses in less than 24 hours THANKING me for solving this mystery.
Finally, I'm sorry you can't see what the issue is and I'm sorry that you feel I should conform to AirBNB's ideal of creating a dozen wishlists. I'm happy to explain it one more time... When I am on the road from client to client I really don't want to have to figure out which wish list I should be looking in. I simply want to see ALL of the properties that I wishlisted that are near my client, and available on the dates I need them. If the client happens to be near the junction of 3 regions I don't want to have to search 3 wishlists. Have you ever worked for hours on a spreadsheet or other document and then the power goes off and you lose your work? It's a terrible feeling and that is exactly what AirBNB is doing to users who encounter this.