As someone who has used a Mac (vs. Windows) box as a working machine for as long as I've had a choice in the matter, this is abject nonsense. Yes, Windows is still a huge presence in the software industry. But denying that people do serious work on Macs is just plain trolling.
If we're going to throw around anecdata, virtually everyone I know who uses a computer to work on these days uses a Mac. This is a vast turnaround from just a few years back, when Windows was virtually compulsory. For much longer than that, it's been University Student => Mac laptop, only rarely Windows. When I meet with folks from Very Big(tm) software companies, they invariably have Macs.
There are definitely domains that are Windows strongholds. AFAICT, none of the major CAD/CAM suites run on OS X (e.g. Solidworks, Pro/E, Geomagic (nee Alibre) Design, etc.) Stuff like major site planning software (e.g. that keeps big airports running) is virtually all Windows.
For all that, it's easy to miss that Mac has for a very long time been on a user-driven vs. enterprise-mandated upwards trajectory. This seems similar to the forces that pushed acceptance of iOS (and Android) into the enterprise: where user demand ultimately broke the stranglehold that the entrenched, enterprise-friendly solutions had. (I'm looking at you, Blackberry.)