I just checked a bunch of normal boutique hotels and their listing inspire much more confidence and are actually cheaper. At this point I have no idea what Airbnb offers that hotels don't do better.
For solo travel tho, I'd rather book a hotel sight unseen than use airbnb, since too many people try to make their couch in the corner look like a nice private room in the listing.
As a business? They avoid tons of regulations there for zoning, public safety, etc. That leads to higher profit margins.
To a consumer? I'm not 100% sure anymore. Except some places where hotels are booked through AirBnB to gain better access to customers
If you look at hiltons on booking.com and booking at hilton.com you'll see different prices, until you go through the hilton.com process and select non-refundable/non-cancelable rates, then they're the same rate, expect if you book via booking.com you don't get any points with the hotel chain.
I am not deeply sold on this idea as a whole, but it seems like having a very low-maintenance van has its advantages right now compared to a hotel room which has probably sat empty for the majority of the last few years. As you say, it seems unlikely that airBNB is explicitly pushing them at the expense of other listings; more likely, it just is a consequence of the world we live in.
[1]https://prtimes.jp/main/html/rd/p/000000586.000030117.html (Detailing a niche hotel where you get to pretend to operate a main tokyo train line and be woken up by the same device train conductors use)