The speed limit should reflect the reality of the road. No, you shouldn't go around tomorrow updating all your speed limits to 85% percentile graded and then try to redraw the roadways to traffic shape to desired speeds. You would do the latter first, then update your signs.

Except in most places, neither is happening. People are driving dramatically over the speed limit because that is the natural speed of the road, and no attempts to change the actual speeds of traffic are happening because they cost money.

So people get to die for the multitude of reasons the article outlines because of political deadlock.

The point of the article is that for 85% of the people driving on the road the speed limit most emphatically does not act as a target. If it did then modifying the limit would be a useful knob you could turn. Since it isn't all it does if give the non-automotive traffic a false sense of security regarding how fast traffic might be coming at them.

I think the idea is to use traffic calming methods to change the 'realistic' speed limit from 35 mph to 25 mph, and then post signs for 25 mph.