We offer hosts the opportunity to block dates out on their calendar but we don't require them to do so. Please keep in mind that they are not running a business. They are going about their regular lives and generously offering to welcome guests when and if it is convenient. They get to make that decision at the time the request arrives. 

Some hosts only get a couple of requests a year. It would be a nuisance for them to log in and mark their calendar every time they decide to go away for a day or two. 

It may make sense for them to mark it if they're going on a longer trip, but even then, some hosts purposely don't because they're afraid to advertise the fact that their property will be unattended. And that's fine, as long as they still reply to any requests promptly to decline. We encourage a prompt response by giving them only 48 hours before a request expires.