As @Cor3 says, also applies to Booking Requests. I did have one guest inquiry in which we messaged back and forth a few times and she seemed like an old friend right away, we just totally connected. She said she was going to arrange her flight and get back to me with firm dates. I didn't want to block the calendar in case she changed her mind, but as I didn't want to have to decline a booking request, when I didn't hear back for a few days, I messaged her again, saying, no pressure, but asking if she was still planning on the trip, as if I got a request in the meantime I'd have to take it. She responded right away, saying she has a fear of flying, which had held her up from booking a flight, thanked me for building a little fire under her a**, booked her flight and booked my place within a few hours.
Turned out we got along so well, that I asked her if she wanted to come back in a few months and house and dog sit for me while I took my annual trip to Canada. She was totally excited about the possibility and we are arranging that.
Personally I won't use IB cause I share my home and I love to have the flexibility to communicate with guests prior to booking. I know I'd get more bookings with IB, but having guests who I know will "fit" is more important to me.