"Rent seeking" has a specific definition* and it is not "I use large capital investments to generate regular payments". Buying housing with the intent of renting it is not rent seeking.
This is Wikipedia, which is as good as most other definitions: Rent-seeking is the act of growing one's existing wealth by manipulating public policy or economic conditions without creating new wealth
In what way does buying a property and renting it create wealth? Isn't buying a property with the intent to rent it manipulation of economic conditions?
There is rent-seeking, rent extraction and the rentier class. All are a part of the process of enclosure. Landlords are included in this but it may not seem that way because enclosure happened so long ago.