You could have made heat treated framerail fracturing horsepower in 1970, but there were no tires available that could lay down a .950 60' time with that power. Lots of the improvement is in the rubber.
But lest we forget that clutch technology is light years above 1970. Not to mention what we have learned from onboard computers. And we have ways to take timing out as some part of the run, put it back in at some part, etc.
All of this stuff adds together to make a quicker run. (And lest we not forget, that the tracks are smoother, better prepped, etc.)
But I like the limitations. Keeps things real.