Weirdly, the article fails to note this is a Windows only malware.
Also, remember when Microsoft themselves were hacked multiple times by Russia? Or when a Russian spy was hired by Microsoft?
Windows has historically been insecure, it could just be that Microsoft is bad at security...
Most malware campaigns target people.
The only reason there is to target individual Windows users is because it's easy.
Whether targeting public facing Windows servers, or the employees' own desktops, it's easy to see why Linux would be more of an afterthought. Windows devices massively out number the number of daily-use Windows devices, which also increases the opportunity for attack.
I do think Windows is something of a "dragon king" of malware due to its design.