“Experience surely should be based on some tangible facts one would assume.”
This is where your assumption loses its legs. Airbnb doesn’t get involved with trying to decipher what events really occurred. As far as reviews go, they consider any guest or host experience a valid perspective. To do otherwise would involve them in long and lengthy investigations with thousands of hosts and guests. Airbnb can’t justify the cost of that. In short, they leave it up to the host and guest to sort themselves out.
Believe me, untrue reviews are experienced by hosts also, and yes, it feels very unfair. In fact, if you were to ask the members of the hosting community, I’m pretty sure the consensus would be that Airbnb sides with guests more than hosts.
Having said all this, I’m sorry this has soured you to Airbnb as a whole. Your host’s actions are extreme - I would guess that most of us, including myself, consider things like the loss or damage of an occasional towel or two to be part of the cost of doing business, and don’t try to go after it with a claim and/or a bad interchange with the guest.
As @Mike-And-Jane0 said, this issue is more between you and the host, rather than you and the platform. Most hosts are not like this.