Airbnb has many listings where there is no automatic reservation - many of them if not most of them are that way. Hosts did not respond to me in a timely manner if at all. This would result in having to wait for a day or two and then cancel your request if there is no response. Then you must send a request to another host.
The website allows you to send requests to multiple hosts at once but if two accept your reservation you still pay fees if you cancel one. This is a major flaw as far as I am concerned. I am not very impressed with this site.