You completely missed the point. Rate of drain is CRITICAL when the phone is on standby, i.e. in my pocket. When the screen is on with a bunch of foregrounded apps, the equation is completely different and rate of drain is not the primary issue.
For example, in screen active mode most of the time clocking down the CPU is about the stupidest thing you can do from battery saving perspective, as short bursts of high activity with long deep sleep cycles are more efficient than dragged out activity cycles on lower clock.
Saving battery is an active fight, and operating systems are always going to be fighting a losing battle against the apps - but by no means should they give up, there are myriad of untapped ways how to make the current situation much better for an average user.
The idea of having a 10% dumb phone in my pocket that cannot do anything does not match with any of my use cases. I simply dont send texts and rarely have to do phone calls. However, it is often critical that i can still open email and maps, for my wife it is critical to take this one last photo for which she has been saving for, and for someone else it is that one last foursquare checkin. Your pattern is not my pattern and vice versa, and there is a lot of improvement room for mobile operating systems to get much much smarter about that.
Yelling panic at 10% is something that my laptop did in 90ies.