The requirements you can choose if you use Instant Book exist specifically because guests who IB do not have to communicate with the host first. Hosts who do not use IB or who do, but also get requests as you do, use the Airbnb messaging to communicate with guests to determine whether we feel they will be decent guests, as well as reading ay past reviews they may have.
If you are simply declining all the requests you receive just because they didn't meet your IB requirements, that's a pretty strange way of running your hosting business, and I imagine that while Acceptance rate isn't a huge deal, as Andrew mentioned, if you decline every request, Airbnb may eventually delist you.
You aren't expected to accept every request, but rejecting all of them isn't okay. You need to communicate with the guests who send requests to determine if they will be suitable guests.
@Brian686