I work at Airbnb (as an engineer). Fact is, most of the negativity seems to be coming from non-engineers since Airbnb has been trying to scale out its customer support and facilities staff by bringing people on as contractors. This is all pretty new and it's really not surprising there are growing pains. But in the past, they've been really good about addressing issues so I'd be really surprised if this doesn't get better in a year.
As for engineering, it's still fantastic place to work. Right now, it's very much in a transitional phase but the good news is they've kept the hiring bar high and are bringing on plenty of talented people (lots of experienced ex-FB, ex-Twitter, and ex-Googlers hopping ship to join us). Yeah, the internal tooling needs work. Yeah, it's still kinda chaotic. But given the kind of growth we've seen, I'd be surprised if there weren't issues.
AirBnB has grown enough that it is now an organization of organizations. Top-down culture is subordinated by the culture of the immediate group. It's entirely possible that these negative experiences happen within some but not all of the groups in the company. So, it's incorrect to draw an assumption that the entire company consists of toxic practices.