I work for a large enterprise and we pay or retain vendors to do things for us all the time, at a much higher cost than it would be to do it in house, because we cannot find/hire/retain the expertise to do it ourselves, and at some point we need to get the work done so that other more mission-critical work can happen to drive the business forward.

Plus, there is value in paying someone to make the find/hire/retain part their problem instead of ours.

We buy the reliability of getting the work done in a timely manner, on top of the work itself.