If what you and o_e_l_e_o are saying regarding data extraction is true (and I assume you both know what you are talking about), that would mean that open-source operating systems are equally vulnerable as close-source ones.
Not necessarily. Windows has far more vulnerabilities in it than most Linux distros, and also generally comes bundled with so much vaporware/junkware/bloatware like Cortana and Bing embedded in to everything and monitoring your keyboard strokes, remote access tools, and other privacy invading trash. Doesn't Windows 10 come with Candy Crush installed on it, for God's sake? Even if my computer is airgapped, I'm not trusting that mess with the security of all my bitcoin.
it certainly shouldn't be any showstopper issues that mean the OS is basically non-functional.
For now. The way that things are moving with internet connectivity being required for a number of software packages, software being rented instead of owned, software moving entirely to the cloud, and other software as a service nonsense, I can easily foresee a future where you have to rent your copy your Windows which will not allow you to do most things without an internet connection.