Interesting to see this pop up again, as I agree with the post but not the bait-and-switch in the title :-P

Open source is not a business model in and of itself, but many very successful companies and large enterprise units are built off open source foundations and the aggressive adoption that that garnered. I'd always urge the framing to shift towards something like; 'open source is rarely the only thing to do, but it's worth doing widely for many commercial reasons'. (in)Famously IBM's revenue from open source services was $2Bn in 2003 before they stopped separately reporting it.