You could be right about these numbers becoming meaningless. But in the meantime, there is a noticeable difference, and that can mean life or death in the jam-packed web dev market that we see today. If cramming as much application logic as possible into the front side continues to shave off milliseconds or even seconds in some cases, then I think that trend will continue.

That said, I hope you're right. A world in which front vs. back end didn't matter with respect to time would be one in which developers were free to reveal far less on the client side, and that would be a victory indeed!