Look, I get the sentiment.
But conceptually, landlords do present a service.
There is time value in being able to call a singular person and say 'my stove is broken' and not have to do anything else.
Yes you can do it yourself if you have the time and skill, it is a hassle finding the right stove, at the right price, getting it delivered or picking it up, finding, hiring, and going under contract with individual people to do installation, managing warranties, etc.
A lot of people don't want to do that, a lot of people are also comfortable paying a premium to have someone do stuff that they don't want to do.
There is value in being a broker, and that is a landlords primary job, the maintenance and responsibilities are abstracted away to the renter.