Don't forget that "covering the mortgage" involves building the landlord's equity, so it's not as if this portion is lost to the bank while the landlord has to depend on appreciation. If I "only just cover the mortgage" while renting for the entire term of the mortgage on a house that doesn't appreciate above inflation, the landlord still goes from owning 20% of a house to 100% of a house over that term.
True but there are a lot of additional costs (maintenance, council rates, depreciation) to owning a house on top of the mortgage. Again only speaking for myself but I have a small rental property and the rent basically only covers the interest plus expenses.
Don't forget that "covering the mortgage" involves building the landlord's equity, so it's not as if this portion is lost to the bank while the landlord has to depend on appreciation. If I "only just cover the mortgage" while renting for the entire term of the mortgage on a house that doesn't appreciate above inflation, the landlord still goes from owning 20% of a house to 100% of a house over that term.