If a blogger is so popular that a lot of his or her writings have been published in book form, can we say he or she is a net writer? Or any blogger can be called a net writer? Thank you very much.
I don't know of a phrase for it. If I were the person involved, I would say "I'm a blogger and I've had my blogs published in book form".
Nor have I met 'net writer'. I have heard -particularly in the Arab Spring, but no longer restricted to that area - the phrase 'citizen journalist'.