Draw you own conclusions...as they say, it is a rough estimate.
http://forensicdynamics.com/stopping-distance-calculator
As some have said that they do 70 when the speed limit is 65, it maybe reasonable to assume that with the limit raised to 70, they may up their speed to 75. In a section of Interstate where there are moose populations, that resulting increase in speed, by the calculator, would add over 30 ft to stopping distance. This 30 ft could be difference between "Boy that was close" and "Hey Bullwinkle, get outta my car!!!!"
Just another side to consider.