You need to learn to read the questions properly, as well as the FAQ. What you have overlooked in your examples is context. It is the context of the question more than the subject material that determines if it's on topic. Here are my interpretations of your examples:
There is nothing in the question to suggest that it's being asked within the context of a system being administered by an IT professional and could just as easily be about a workstation. It's therefore far more appropriate for the Unix site.
Borderline. The question again has no context. It could just as easily be referring to someone's workstation, trying to set it up to allow his/her friends to FTP (we get that a lot).
I agree with you on that one.
A clear-cut shopping questions, which is always off topic.
Another shopping question.
Same as the first two examples - a much better fit for the Unix site.
Should not have been closed.
I'll repeat, you need to read both the questions and the FAQ much more carefully.