Generally you're right that the wide sections are where you want to focus your attention when looking for optimizations. The point I was trying to make in the blog post is that we had to take the flame graph visualization a step further to eliminate the noise obscuring a major hot spot. The large number of broken stacks was one of the first hurdles we had to cross to improve the clarity of the visualization.

BTW, this is a different flame graph and optimization than the one discussed in the YouTube video. We use flame graphs extensively throughout Netflix.