Surely the flaw in this benchmark is that they're comparing Jetpack with popular plugins that do the same job. What I find is that if I'm using Jetpack, it's easy to be tempted to use more features: whereas if I don't, I'm more likely to seek out the lightest plugin (i.e. not necessarily the most popular), or to find a way to avoid using a plugin altogether. The result is a much lighter, faster site (according to P3 and speed tests).