That doesn't seem like Airbnb's problem though. I wouldn't think that's the only reason unless the government is making them do it. That's entirely possible, but at the same time, the information they're asking for is a gold mine for marketers.
I did say it's possible the government is pressuring them do it, but that's something I suspect Airbnb could fight if they were motivated to do so.
(Chargebacks do make it their problem though, so my premise was false anyway.)
Know Your Customer laws are the reason given by AirBnB themselves: https://www.airbnb.ie/help/article/3004
OP complained about "your bank account numbers, entire transaction history, financial data, and contact info." Normal KYC does not include all this.