Source: I am a landlord and I could temporarily destroy either of my roommates' livelihoods at the drop of a dime whenever I please. As a result, they are basically my permanent friends until they save up enough to move out. The difference between me and others in my position is I understand these are material relationships more than social relationships, and the only way to change that is not being the landlord.

When Marxists want to get rid of landlords, this is what they mean. They simply want more social relationships rather than material relationships. That's why it's called socialism.

I just would like to nuance the power a landlord holds. It really depends where you live. I live in Germany since a while now and renters have very very strong rights, they can just as well make the life of the landlord impossible. They can stop paying and it’ll be months, maybe even years, before he can kick them out.