That's true, but their apathy or ignorance is a threat to any networked device. There's definitely an argument for "my device,y software, my rules", and technically you can run windows 7 as long as you want, but Valve shouldn't be perpetually expected to support deprecated software either. In their case specifically, if would be hard to ensure their anti-cheating software isn't being circumvented at the operating system level, meaning the experience of everyone on any OS would be lowered by continuing to support a 14 year old version of Windows.