CxOs want to be dependent on someone else, specifically suppliers with pieces of paper saying "we are great, here's a 1% discount on next years renewal"

If the in house tech team breaks something and fixes it, that's great from an engineer point of view - we like to be useful, but the person at the top is blamed.

If an outsourced supplier (one which the consultants recommend, look at Gartner Quadrants etc) fails, then the person at the top is not blamed, even though they are powerless and the outage is 10 times longer and 10 times as frequent.

Outsourcing is not about outcome, it's about accountability, and specifically avoiding it.