My personal (unproven) theory is that the non-profit model works well for ventures that require very little entrepreneurial judgment, but poorly otherwise. Vanguard basically follows that: they mainly sell index funds, which a well-trained monkey can run.

Similarly, it makes more sense to have a non-profit coffee-buying employee group to buy coffee (at places that don't provide it for free) rather than pay a vendor to bring it in. But that's not because profit-making is an inherent drain on efficiency, but because the "judgment" that those profits are "buying" ... doesn't add much value.