Most of these companies aren't managing their own data centers at least for areas that use a large amount of compute. Banks and the like that have their own data centers, generally are still using some type of contractor to manage the physical real estate, network connections, ect. even if they are the ones purchasing the servers.

Come on, that’s like saying Google has no business having datacenters because they are an Advertising and Search company. Of course large companies will have contractors to scale up and down. They will have FTEs doing System Administration and Software Engineering on the servers.

As if Google or Amazon isn't using contractors for some of their stuff as well?