The article does state they were included, but is it "obviously" true that they should be? Who is more of an "investor", someone who purchases a primary residence to build equity or someone who purchases a second home to vacation in, spending large amounts of money to maintain it and allowing it to sit empty for long periods of time?
In what sense? An investor seeks a return on their investment. The former achieves this. The latter spends money for pleasure. I suppose you could argue that they are an investor seeking non-monetary return, but in that sense everyone is equally an investor, just with different goals.
