There is the "things guests must know before booking" facility (wording paraphrased). Apparently, this is presented to the guest at the last step in booking, and requires their acknowledgement. It gives you the opportunity to present critical house rules or limitations at booking time and make sure they are aware. IIRC, It's very limited in number of characters you can enter, so you have to be very brief.
But aside from that, the Airbnb message system, while useful and important for creating a record of dialogue with the guest (which should always be used when conversing about issues that have or may arise during their stay), is by comparison to other mediums, rather slow and limited...
...and apparently unreliable as well. We've had many guests who claim they never received any notification of any messages on the system, and therefore never looked, resulting in your message to them being missed entirely.
And that's not good... for example if they're confused with driving directions, or something in the house isn't working, or they're asking for a pharmacy, or looking for a restaurant recommendation for this evening... They need an answer. Now. Not tomorrow.
Responsiveness is a critical factor in successful hosting. Not just because Airbnb says so, but because it's just good business.
Guests perceive nonresponsiveness or inability to receive information as a frustrating red flag, and will naturally rush to judgement. And that often taints their reviews, regardless of how good their experience.
