This does give AirBnB a reason enshrined in policy to take consistent action against misbehaving hosts, something that was lacking previously.

Also, I am not sure why you are conflating AirBnB’s authority with a local government - or course AirBnB won’t address the issues you cite in your last paragraphs as that is not their job and to think it should be is totally ridiculous. We have local and state governance to pass laws regulating behavior that is not good for society at large. AirBnB’s job is to generate value for shareholders all while operating within those bounds.

Why wouldn't it be AirBNB's responsibility to prevent hosts from operating illegally?

You know what you could do?

1. Not allow Airbnbs in residential areas

2. Force each Airbnb host to list the address

You know, like hotels

But they get to remind everyone that they're the "good guys", and they're "trying"

There are properties with openly visible cameras in the interior, which are typically pointed at reasonable locations to watch (like the front door), but being inside, they could potentially be listening to conversations that they don't really need to be. Those cameras should really be on the exterior of the property. This fixes that.

My guess is it will stop property owners from using cameras openly indoors as they have been allowed to before.

Hidden cameras aren’t as useful if the host can’t take any obvious action from it. So it does have an effect