That line is in response to the question, 'Is Pinterest fundamentally feminine in some way?' The answer of no in that context is that Pinterest is a derivative behavior associated with 'women's magazines' which is also not fundamentally feminine.

I think it means that Pinterest is a modern scrapbook for women who make scrapbooks, not all women. Not representative of an entire gender, but of a subset.

i think that it's making an implicit distinction (which might not exist) between social and biological cause. the argument is that it's rooted in a social activity, which might be (implicitly, is) constructed / learnt, rather than innate.

(and it's a better article than i expected - credit for being honest enough to detail the "defined by consumption" aspect in fairly neutral terms (or maybe it's just the male in me that finds that a little crass? don't you know that all value comes from winning the game?))