Obviously the zipper merge is ideal. But human drivers, especially in a high student population area with overcrowded roads and a ton of continuous construction, are not ideal. If I merge early, I avoid the following:

1) Trying to find a non-existent spot to merge at the merge point
2) People blocking me from advancing to the merge point
3) People getting road rage and following me to work so they can call the police on me because I "cut them off" where the road merged (really happened)

However, I also leave a gap when I merge early between me and the car in front of me so a late merger can merge effortlessly. That helps everybody.

So yeah, it is less efficient, but I also see so many close calls with late mergers because people are daft and selfish that it's just not worth trying to educate in a live situation.