Perhaps the fact that guests do get granted 'Extenuating Circumtances' is why they cancel, so the easier Airbnb makes a gift of it, the more cencellations hosts will have. True.
I am not sure what is the percentage of guests wanting a full refund under Airbnb's infamous 'Extenuating Circumtances', and actually getting it, it would be interesting to know what that number really is.
The problem for hosts perhaps lies with the very short notice of cancellations operating with the common Strict and Moderate policies. It would help hosts so much more if they were given at least 30 days to find a booking replacement.
Over 4 years, I have encountered about 5 cancellations that have qualified for a full refund under that clause (3 being very suspect), but have had about at least 15 situations in which guests have lost their 50% of their booking fee, so it has even out in my case.
And yes, Airbnb does favor the guest, no doubt.