I'd add that in my experience, when you are close to the action, the cynic "golfing nepotism" take is usually missing a point of view that is far more rational; just far from the developer/architect that is dismissing the decision. Perhaps not technically optimal, or fair, or even legal - but even so, more akin to "I know this person delivered in the past, and the alternative is also good on paper" or "I really need to save my ass" (nobody got fired by choosing IBM) or "business-wise, this technical recommendation I don't really care for". Perhaps I'm optimistic but in general I don't really think (or want to believe) that people are quick to wage their careers on an acquaintance that is clearly selling something as part of their job, unless the stakes are really not so high from their point of view. Then again, open a newspaper :)
This is just one example that was made public due to the federal case, but there is no doubt that this kind of activity is quite common in corporate America at all levels. https://www.justice.gov/usao-ndca/pr/former-netflix-executiv...
A solid understanding of behavioral psychology may make it obvious, but like you mention, one could also just open a newspaper.