Writing/ Reading

From Margaret Atwood's "Negotiating with the Dead":

I would like to begin by talking about messengers. Messengers always exist in a tringular situation - the one who sends the message, the message bearer, whether human or inorganic, and the one who receives the message. Picture, therefore, a triangle, but not a complete triangle: something more like an upside-down V. The writer and the reader are at the two lateral corners, but there's no line joining them. Between them - whether above or below - is a third point, which is the written word, or the text, or the book, or the poem, or the letter, or whatever you would like to call it. This third point is the only point of contact between the other two.
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The writer communicates with the page. The reader also communicates with the page. The writer and the reader communicate only through the page. (p.113)

But how does blogs change this relationship? Through blogs, the readers become other writers/ contributors. All writers communicate through the webpage. Although there are other readers who only read, don't blogs change not only the relationship between writers and readers but also their definitions? Where does one role end and the other begin?

Writing/ reading? Writing = reading? Writing =/= reading? Writing is reading when ...? Reading is writing when ...?