If the flight is not full they may do this, but not always. I've been on plenty of flights where ES was jampacked, but there were lots of empty seats in economy. On one occasion I had the first row of economy to myself, whilst all the pax in ES were happily rubbing shoulders and elbows. The only explanation I can think of is that for some reason they could not or would not move the cabin divider farther aft.

Johan