FWIW I have seen it recommended multiple times, including from hosts, that it is polite to ask a host if they have availability via airbnb even with the instant

FWIW I have seen it recommended multiple times, including from hosts, that it is polite to ask a host if they have availability via airbnb even with the instant booking enabled. I agree with you but if that message is as widespread as I've assumed it could explain what you see