How is "we are not obligated to provide an explanation" a valid reason? Of course they need to state why you were banned? Dystopian nonsense. Stop using AirBnB.
The potential downsides are huge legal costs and the upsides are almost none, so any business is wise to keep their mouth shut unless through lawyers. Same reason why you don't comment on people you don't hire.
The same can be said for starting a business in the first place.
A business is "wise" to keep its humanity and treat other people with respect.
And we as consumers care about that why? It's not my concern that providing an actual answer might get them in trouble.
It's not, I'm just stating why I believe businesses don't always explain their actions.