Landlords do not provide a service.

They take otherwise-purchasable properties off the market, then make money off preventing other people from owning them in perpetuity.

Some landlords also offer property management services, but that is a separate field entirely. It would be fairly easy for an apartment building to consist of entirely owner-occupied units, who could then join together in a co-op to either put individual local contractors on retainer for things like plumbing, electrical, and miscellaneous repair services, or find a one-stop-shop company to hire for it.