Here's an idea: Stop pushing InstantBook. People are pressured to turn it on in fear of being penalized in the search ranking.
InstantBook has now also been identified as a primary tool to stamp out race discrimination, while of course also resulting in extra revenue for AirBnB: win-win. For AirBnB. Not for hosts, and actually also not even for guests, when hosts don't get the opportunity to warn the guest about certain things, set expectations, etc.
So stop this penalty stuff but instead make 'InstantBook' a switch when guests do a search. When a guest really wants instantly bookable places only then they can check the box in their search, much like they can filter for 'entire place' or the number of people, or their price range.
That still achieves the same in that hosts do actually may end up getting fewer views IF INDEED guests also think that InstantBook is a good thing. But if it doesn't matter to the guest because they actually also prefer to just send the host a message first to say "hi", and ask a couple questions to see she's responsive, or because they wouldn't want to book with a racist host anyway and would much rather reward a host who is welcoming to every creed and not a racist moron who ends up hosting them anyway.
And it acknowledges that a friendly guest-host chat and informal vetting WAS THE VERY THING THAT BROUGTH AIRBNB SUCCESS and is actually THE strong point that makes AirBnB much more of a friendly community rather than just a booking site.
Then everything will be well, without some behind-the-scenes black-box penalty system pulling strings on your listing merely because you have legitimate constraints on accepting bookings.
Note: I'm not saying that InstantBook isn't useful in some cases: for example when a guest needs to book something for the same day or next day then yes, InstantBook will work a lot better than having to send an inquiry and possibly not getting a response until the next day, or find out that the place isn't availabel on short notice.