@Linda3449 While some hosts say they are in areas with such heavy competition that they'd be dead in the water if they didn't use IB, other hosts have used it but gone back to requiring requests, and some, like me, have never used it and never intend to.
It depends on a number of factors- the nature of your listing, what you personally feel comfortable with, whether you are someone who likes exchanging messages with prospective guests, or someone who just wants bookings and dislikes back and forths with guests.
As a home share host, I would never feel comfortable having someone be able to book without communucating with them first. And building a bit of rapport through the written word makes it feel, both to myself and the guests, like we're not total strangers when they arrive.
A listing that could easily attract partiers may not be the best choice for IB, and I've read a lot of posts from hosts who've had to deal withh house trashings who decided to turn off IB so they could personally vet guests.
IB works really well for some hosts, though, and they tend to be pretty experienced hosts, or have listings where they live on the same property, or next door, so guests can't get away with bad behavior, or the listing is such that it attracts the types of guests who just aren't the problematic types.