Whether chronological makes sense is a product of the number of times you log in and the number of 'friends' you have (and the number of posts they make).

I have 140 friends. I log in a couple of times a day. I have filtered all their crap. I want chronological order.

If I had 1000 'friends' who posted all day, then I would want a way more filtered and special-sauced feed.