I think two can be fine, if just to cover weird situations you might find yourself in (cosigning with somebody, somebody dies and leaves it you, or I guess I don't really mind a "summer home"). I think beyond that though I agree.
Private landlords are not as bad. If everyone had only one house there'd be nowhere to rent unless you only want to rent the room.
Now corporate landlords. They own so much real estate it's practically a monopoly. And as a business they're profit driven and exploit their tenants. I think renting wasn't so bad before companies started investing in real estate.
This is the real problem! Companies that own many many homes/ apartments are disgusting to deal with - everything is profit driven. Lost my mom recently and her house is transferring to me through the court so every day i get a dozen calls from investors, -" I'm sorry for your loss; can i buy your house? AAA Property Mgmt."
I think having multiple houses(for different seasons or whatever) is fine. It is the financial exploitation of housing that is wrong. You shouldnt be able to rent houses.
I would say have as many houses as you like and rent them but there should be universal rent control and progressive property tax (the more properties you own the higher your tax).