This isn’t about computing but about specialization. Should McDonalds be in the business of operating Data Centers? Or should they just buy it from those who do it best and focus on selling food?
Should they be in the business of cleaning bathrooms, or should they just outsource that to a temp agency? Sometimes specialization pays, and sometimes it doesn't. Perhaps it doesn't make sense for McDonalds to run its own web and corporate servers, but doing so might make a lot of sense for more tech-centered companies. And I'd guess a server farm is miniscule compared to the size and complexity of their ingredient supply chains.