That was a kind of aggressive way for me to express that, but, in all seriousness, the reason is that:
Being a "landlord", that is, very specifically, an "owner of houses you don't live in, but rent to people for profit", is a way to live that is inherently abusive to the people you rent to.
You have ownership of a basic good people need to survive (housing), which is effectively scarce (because it's not allowed for just anyone to build a house without incredible amounts of money, even homelessness is fairly illegal in many places), and you say to people:
"Either give me a monthly fee for me to allow you to have a roof over your head, or I'm calling the police (the only people allowed to be violent in the country) to kick you out"
It's a way of making money, where the owner doesn't do anything helpful to society, except find people who are desperate to survive, and milk them of what they make.