The only argument that anyone ever has for landlords is that the provide a service, but that service is property management and could be done by the state without the need for profit (and also it's not a real job if it's for a single unit)

Of course this doesn't even address the fact that by their very existence, landlords are a parasite on the free market through their monopolization of assets. If housing supply exceeds demand then the value of houses should drop until it reaches an equilibrium. By sitting on property, landlords ensure that supply doesn't meet demand so the price of housing doesn't decrease. This means renters can't afford to buy a home then the landlord steps in and parasitically extracts rent from the otherwise homeless renter. This in turn creates the rental market which incentivizes landlords to maintain a supply that does not meet demand (by keeping a small number of units empty or discouraging development) so that rents stay high.

There is also the very nature of the landlord-tenant relationship in which it is in the best interest of the landlord to charge as much rent on the cheapest housing possible, but it is in the best interest of the tenant to not be homeless. In the relationship between a landlord and their tenant(s), the landlord's interest is to extract wealth to the brink of the tenant's financial ruin. In the relationship between all landlords and all tenants, it is the best interest of the landlords to maintain a surplus of tenants who are then homeless or inadequately housed.