Let’s be honest: there are two APIs.
Amiad is discussing Airbnb’s Partners API, which faces huge contraints, both geographically and technically (it’s impossible to collect the details of a listing for example) , which makes any PMS’s job harder.
Smartbnb (and Guesty to some extent) is using Airbnb’s “Native” API. It is a different service, which can be used anywhere in the world, and doesn’t have the same restrictions.
You, as a end-user of Airbnb, have received a license to use this API right from their Terms of Service.
As for our service, our users are the ones that talk best about it: