Matching speed does a better job of filling both lanes evenly and reduces the amount of backed up traffic. The slow lane is what backs up to prior intersections. Matching speed is what allows the slow lane to clear up and prevent affecting upstream intersections. You're point isn't actually relevant to what I've described because the lane is fully utilized in a proper zipper merge with speed matching.

So I'm not ignoring the purpose of the merge lane, and I'm not advocating early merging. I'm describing the key aspect of zipper merging that the cruise ahead people are missing.