Given Linux's history as OSS, it has historically been easier to be familiar with the inner workings of Linux than Windows simply by having access to the code. Other than reading System Internals, becoming MCSE certified, etc. it was really hard to know much about Windows. I'm not saying every Linux user has read the source but being built on top of OSS does allow the user to dig deeper if one wanted to. I say this as someone who started out his career in Windows and Microsoft and then later went to Linux (because I went from corporate to startup). It's much easier to pinpoint a problem with OSS and Linux, especially in situation when the documentation is lacking. It took me a lot less time to have a decent knowledge of Linux and OSS systems than it was for me to know the equivalent on Windows and Microsoft.
This effect gets compounded when you consider an entire ecosystem.