In my experience, it used to be more like flat-sharing early on but lately I’ve seen it be more business-like. Some parts of the world don’t allow for short-term letting of an entire flat. Somebody has to live in it.
It can also vary by location. For example, I’ve never had my own place in Italy (and a few other countries for that matter). But when I set up a visit to Slovakia for mid-April, I couldn’t find a private bedroom in someone’s place for that set of dates in that part of Slovakia.
As a solo traveller, I actually had some of my best travel experiences in a hosting situation rather than having a whole flat to myself. You also get to know a bit more about where you are through the host. In Florence, the homeowners had some family over for dinner and invited me to join them. Got to practice my terrible Italian and some other family members tried their terrible English. When I visited Sweden, I got invited to an island off the coast of Gothenburg along with a few other people for a meal on Easter. My host in Helsinki was a boxing fan and wanted to watch Anthony Joshua vs Wladimir Klitschko. I set up the feed through his TV and watched with some people he knew rather than yelling at a laptop screen.
The worst ones are the ones where a family owns a house and rents out every vacant bedroom individually in it. I always check to see what other properties the host has on AirBnB if they have any just in case this exists. Last thing you want is to basically find yourself in a guesthouse in a different form.