First off I am very happy to see there's now an official place for host feedback and featuer suggestions.
I have voiced this concern before and I will say it here again. Hosts need a safe way to block people from contacting them or booking their listings if they have instant book turned on. I have this guest who i have hosted before and do not wish to host again, but now he keeps on booking my listing even though i have already cancelled him and told him i don't want to host him. Already contacted airbnb but if he keeps on booking I might be forced to turn off instant booking.