Comment by gumby

Ronald Coase got the Nobel prize for answering your question, most famously in his essay "The Nature of the Firm", considering it to be transaction cost.

So there is no real benefit to couple the decisions of the catering staff with the company’s marketing or engineering teams; on the other hand an organization that just does commercial catering might do better on, say, hygene (practical or following regulatory requirements), or developing local suppliers of organic food in various locations.

On the other hand there could be the world’s best team in thermal management, but the company still would be better off having an in house team that’s still quite good but can be tightly coupled to the engineering development teams.