What you are finding is that the policy at ABB does not seem to be applied equally or always fairly, you will see a lot of posts like this and it is true of both host and guest losses. You should only have been charged the depreciated value of the item damaged, not the full replacement value.
ABB Host Guarantee Terms and Conditions state:
“Actual Cash Value” means the amount it would cost to repair or replace damaged or destroyed Covered Property as a result of a Covered Loss, measured on the date of occurrence of such Covered Loss, with material of like kind and quality, with proper deduction for obsolescence and physical depreciation.
I have had several damage claims (mostly early 20 somethings that throw a party and trash the place and break a few things) and I have always resolved it through the resolution center with the guest and with the support of ABB (ABB has never been out of pocket). You should have been given the ability to work it out with the host, but the rep didn't seem to take it far enough. BTW: ABB usually sides with guests.
You do have recourse, you could make a claim with your credit card company and they may charge back ABB if they feel ABB has violated the terms with them. You also can escalate this with ABB and force them to take it to binding arbitration that is required under their terms of service or take the chance and go to small claims. Note that going to small claims is in violation of the terms of service, but the host would need to know that.
In the end what's fair is fair, if a guest damages something they should pay for the depreciated value and the host should accept that some level of damage is a cost of doing business. Unfortunatly many hosts are renting out "their" homes so there is an emotional attachment with any loss.