[clevernickname]

The simplest explanation is that the performance benefit of using Windows and implementing just about any Windows-specific design is outweighed by the cost of the Windows licensing fees, when compared to a measurably worse-performing Linux or FreeBSD solution that costs nothing. So very few bother to treat Windows versions of "backend" software as anything but an afterthought.

[dhoe]

It's not even the licencing fees in my opinion. It's that it has had the equivalent of 200 Potterings run amok in it for 30 years. There are so many things that will eclipse any advantage from IO completion ports.

[supernovae]

Not really... the license model provides support and creates fairly standard releases by which you can more easily leverage. If licensing or selling software is your thing. If all you need is something good enough and cheap then licensing could get in the way