Mm, not necessarily. A bed and breakfast is a lot more work than being a landlord. I think some landlords might be okay with piggybacking on someone else's willingness to do a lot of the work.
Maybe we will see a future where rentals spell out the terms of what you can do in regards to airbnb and what their cut is in such cases.
I think part of the problem is that running a temporary place - like a hotel - is regulated completely differently than running an apartment complex/building. By accepting money from their tenants, they would be implicitly running an unlicensed BnB anyway. Probably not particularly legal.
Maybe that is fever talking. I don't know.