The "Doorman fallacy" is an argument that replacing them is impossible because of all the other things they do. The fact that the other things are not as valuable indicates that while they do a bunch of other things, the main thing is the main value they provide in most cases.
There will be cases where they stick around (luxury hotels, etc) where the ancillary benefits are the point, but there are many cases where the primary task is the economically valuable thing.
There will be cases where they stick around (luxury hotels, etc) where the ancillary benefits are the point, but there are many cases where the primary task is the economically valuable thing.