Before you hit 2000 rep on SO, edits to questions and answers are peer reviewed and if accepted, the editor is awarded 2 points. After you hit 2000 rep and gain the ability to edit questions and answers yourself, the editor is no longer awarded the 2 points. Why is that?
After 2000 reputation, your edit are no longer peer-reviewed before they are accepted. You could easily game the system to get extra reputation.
The bonus reputation that is given before you have 2000 reputation is to help people to get to higher reputation gap faster, so that they don't need to have their edit peer-reviewed. Once you have reached 2000 reputation you no longer need that little "boost" since you have reached the reputation gap where your edit take immediate effect.
I'm sure there is a duplicate, though I can't find it, but the reason is simple — the edit points are meant to encourage user participation for newer users. By the time you've reached 2000 points, you have proven significant participation, for which you are rewarded the right to edit freely.