the most capitalistic thing someone can do: you use your money to get someone else to pay [you]. You [lower your overheads as much as] you can get away with, and when you actually [maintain or improve your assets], your [customers] get a [cost increase].

Your argument is more aligned to capitalism in general rather than something particular to landlording. Your argument is applicable to leased vehicles and other businesses as well. Your argument incorrectly rests on an assumption that landlords simply raise rent high enough to cover all their overheads, but like any other business, landlords are beholden to market rates. If the rent is too high, then you have a smaller pool of potential tenants and it's less likely they will be long-term tenants. Also, if a landlord has mortgaged a house to rent out, it's unlikely that the rent he can collect would come near to covering the sum of the mortgage, the rental-insurance costs, the property taxes, maintenance, and other services. Property taxes alone can be several month's rent. Whenever someone assumes that mortgaged landlords are skating on rental income, I assume that someone doesn't know the true costs of owning a house.

What's really happening for mortgaged landlords is that they are using your rent to build equity in their investment faster than they could otherwise.

The prevalent anti-landlord sentiment seems mostly to stem from bad experiences, rising rental costs, and the notion that landlords are somehow "getting something for nothing". Only the first two points are fair grievances. If you're going to take it further and propose that the owner of an asset (real estate or otherwise) cannot hire their property out, then you are striking at Capitalism itself. If you then nuance your argument by proposing that housing is a special case, and that housing rentals should not be a thing because we all need houses, then you're obliged to consider other businesses as well. One might consider owning a vehicle essential to life; should we do away with car rentals? After all, you're paying Hertz's overheads. Groceries? We all need to eat right?