There are also probably lots of startups that would create a complete mess of it. Picking / evaluating vendors is hard and super risky for the average manager. While I personally would seek out more nimble vendors, I certainly understand the attraction to established shops.
Like in "nobody ever got fired for choosing IBM"? Seems like they've just copied a page from an the old book... and this still works, and lots of more competent startups who could do their jobs better will not get those contracts.