@Juan63 It's definitely still a business to rent private rooms in a shared home where the host lives. Many entire home hosts seem to think that home-sharing is more in the realm of a "hobby", but I don't consider pulling other people's hair out of the shower drain and doing mounds of laundry much of a hobby.
I do think it's true, though, that home-share hosts have less overhead in general, percentage-wise. Utility bills, for instance. Yes, if I am hosting a guest, they are going to use more electricity, water, etc, than I would if I was here alone. But that just means slightly higher bills- if it's an entire home, one would have to have another electric account, for instance, which usually has a base charge, whether there is any electricity being consumed or not. The property tax bill for a home-share host isn't more because they happen to rent out a room. We can usually manage to do the cleaning ourselves. We don't have to spend gas money to get to our listings.
So even if a host provides a space and amenities for guests in their home that might be equivalent to the space and amenities of an entire studio apartment, even if the studio apartment already has the mortgage paid off, the home-share host's overhead is going to be lower.
However, a home-share host can also have a bad business model, for sure, if they have gotten themselves into a situation where they depend solely on that income to pay their mortgage and all their other personal and business expenses.