Yeah, that little scam has being going on for years too, @Sandra856 - this one being an actual Airbnb scam (as opposed to a rogue guest scam), tricking unsuspecting hosts into being the canceller, rather than the cancellee.
Why do they do it? They do it because everything that benefits the guests (and swings them a refund that they really shouldn't be getting), also has hidden - but quantifiable and lucrative - benefits for Airbnb... boosts their brand image, generates goodwill, guarantees them future business from the happy, placated guests etc etc. (Exactly the same as the despicable Extenuating Circumstances policy)
So despite hosts complaining bitterly about this shady practice ever since they first started getting stung, Airbnb just carries on doing it, regardless.