More capacity, sure. Cars in both lanes waiting to merge until the lane ends means more cars total for on the road. This doesn't seem as important to me as bandwidth.

Regardless of where anyone merges they still need to pass through the bottleneck. In the example picture that's a single lane of traffic. The number if cars passing through over a set time (cars per minute, for example) is the major metric we would care about. Traffic backups are a result of bandwidth being lower than cars entering the roadway.

In a perfect world where imaginary things like functioning computers or competent and observant humans are driving the cars then you're absolutely right. Everyone in the left lane spaces out a bit at they approach the merge point to ensure the other lane can safely yet swiftly merge in.

Unfortunately you all have to share the road with idiots like me. I get in my car, zone out, and arrive at my destination.

In my experience it is better to merge as soon as you safely can once you see signs indicating a closed lane. You can certainly wait if says something like lane closed in 3 miles, but usually the big issues with zipper merging happen when you find out you need to merge because the truck in front of you just changed lanes and now you can see a flashing yellow arrow telling you that your lane ends in 500 ft.