that because the adverts directly underneath the question stop you seeing whether questions have been answered, more and more answers are posted sometimes hours after the original posting.
This can make a poster feel a little stupid when they scroll down to see their answer only to find that it was answered ages ago.
I am not sure that this explains such actions on questions answered hours or even days ago and now not on the front page. In some instances the late replies are duplicated too , one after the other??