From individuals?

Anecdotally: I've rented 5 different single-family houses in my life. All of them were rented from individuals.

Only 1 out of the 5 had a landlord that owned some other stuff that they also rented out.

For the remaining 4 out of 5, the landlord only had that singular property to rent: They lived wherever they lived, and they also had an extra house for whatever reason that they rented to me.