Hotel room night tax rates are almost always much higher than general sales tax rates. The hotel might pocket more if they sell a room for $200 + hotel tax + $50 resort fee + sales tax rather than $250 + hotel tax.
The complaint is not that the fee is problematic in and of itself, it's that the fee isn't revealed until after your booking is made, usually not until check-in.
Maybe I'm wrong, I don't want to put words in that user's mouth, but my interpretation was that they'd called resort fees are a scam because they only show up after you've booked your stay. That's the scammy/fraudy/dishonest part of the transaction; without it I'm not sure there's anything to complain about.
But I also consider them a scam in practice because hotels & OTAs go to such lengths to hide them during the search process. By advertising a rate that doesn't include these fees they are advertising a rate that simply doesn't exist.
It is (sadly) the default practice in the states to advertise the price of basically everything pre-tax, so at a minimum consumers here expect for tax to be added (though folks new to booking a hotel probably don't know about occupancy taxes). But for a hotel or OTA to advertise 2 different hotels, one with a $30 / night resort fee, as both being $199 / night is also a scam.
Hotels do this for banquet & convention services as well. Everything is "plus plus", meaning plus tax plus a service fee %, usually 20% in my experience. Your $10k banquet hall rental is really $13k if the tax on it is 10%.
My understanding is that when you book through an online travel agent, the regular room rate is subject to a commission of up to 30%, while the resort/destination fee is not. That's why many hotel chains provide incentives for customers to book directly with them.
I've heard in some jurisdictions outside of the US, hotels are required to show the total price including all taxes and fees when advertising rates. So if AirBnb isn't doing this, it could be a problem.
According to the newspapers in Las Vegas, which report on this frequently since it's the resort fee capitol of the world, the resort fees are used to lower the base price of the hotel rooms so they look more attractive on third-party web sites.
Resort fees are still taxable.
Of course, the calculation is not that clean, since maybe the resort fee is also used to obfuscate prices which results in people paying more.
As for the tax collector, resort fees and whatnot have been commonplace for the 20+ years of my adult life, so either the tax collector is a corrupt idiot, or the hotels have a legitimate claim that the entire cost of staying at a hotel is not subject to lodging taxes.