Technically, you are supposed to merge at the end of the lane, not when you first know it is dissappearing.
The lane exists so you can use it, if you merge early why wouldn't someone else drive past you to the end? If they wanted you to merge that soon, they would have blocked the road at that point.
Traffic moves better through a merge area if everybody merges at the point the lanes end, and if people cooperate by alternating.
When people merge early, it makes everybody mad, people in the continuing lane get to thinking they already let people in so they won't do it again, the people who came in get mad when others drive past them, and the people who wait for the merge point to merge get mad that nobody lets them in.
A caveat: In cases where there is a "merge lane" specifically set up for merging, you want to merge during the last part so nobody has to actually stop, rather than driving to the bitter end and then having to cut into moving traffic. Usually these are normal merges marked with arrows at the point where you are supposed to start merging (the Washington Beltway after the 270 spur entrance is like that).
I was thinking of lane closings due to road repair, accident, etc. Not the built in merge lanes. And yes, they drive right up to the barricades and EXPECT the next car to let them in. 99.5% of the traffice has vacated the closing lane before that point - I find it hard to believe that everyone is wrong except the one who feels entitled.