Bad metric
"Windows 8 [...] racked up plenty of sales"
Technically that may be true, but we all know how Microsoft gets to count its "sales". If Windows was not the de facto universal OS pre-installed on every PC, but had to be bought in addition to the PC, then those sales numbers would be drastically inferior.
There has always been enormous effort deployed in trying to find out which OSes are actually used, and that gives us market share of IE figures and such.
Yet we are still given sales figures in any piece that tries to expound on how important the latest version of Windows is. That is not the proper reference, and we should only hear about it when reading about Microsoft share price.