@Dorothy226 You may have communicated with the host before actually booking, but you still could have gone on to Instant Book. We don't know if that's what you did.
There are 3 ways a guest can book.
With Instant Book, you just click on "Book now". As long as your payment goes through okay, the booking is confirmed- host approval isn't required.
If a guest sends a Request, the host has to either accept it or decline it within 24 hours. As soon as the host clicks accept, Airbnb will proceed to charge you and confirm the booking.
If a guest sends an Inquiry, because they have some questions before committing to a booking, the host has the options to simply message back, pre-approve or decline. The difference between pre-approval on an Inquiry and accept on a Request is that the guest has to take an extra step to book after a pre-approval. You aren't charged or confirmed just because the host pre-approved you.
The reason hosts are allowed penalty-free cancellations on Instant Book is because the host doesn't have the opportunity to read a guest's prior reviews or communicate with them before a booking is confirmed. (There are a few standard requirements a host can set for a guest to IB, like prior reviews, verified ID, a profile photo, but guests don't see that- they simply won't be shown the option to IB if they don't meet the requirements)
With a Request or Inquiry, it's assumed that as the host has 24 hours to look at the guest's reviews and communicate with them before deciding whether to accept or not, they really shouldn't need to cancel.
A guest might Instant Book, then the host finds out that the guest hasn't read all the listing info, or ignored it, and plans to bring more guests than they booked for, or bring children to a no children listing, or says something sketchy that makes the host wary about them. So they might then have a good reason for cancelling.
Not all hosts allow Instant Bookings. Many of us want the opportunity to decide for ourselves.