What is always missed in these discussions is that history has already proven low downforce doesn't work, a fact Stewart seemed oblivious to in his shots at Stefanyshyn's racing credentials during his interview, illustrating that credentials doesn't always mean command of the facts. The first version of the 5&5 Rule debuted in 1998. It was designed to lower downforce and thus reduce corner speeds - the rationale cited was the same then as it is now - and increase passing, it accomplished neither, to where late that season Terry Labonte publicly stated the package had made the racing boring, and NASCAR dropped it in November.
Downforce increased. In August-September 1999 Goodyear made a tire change to a compound designed to battle Hoosier in Winston West racing; it had more stagger and debuted at Michigan.
Late in that 1999 Yankee 400 the battle for the lead swelled into a spirited nose to nose fight reminiscent of Michigan of old - i.e. of the bias-ply tire era.
Another heated battle for the lead developed at the Delaware 400 at Dover that September. But by 2001-3 Goodyear was running a much harder tire compound. In 2004, after heavy lobbying from Rusty Wallace and after John Darby took over the garage area, NASCAR tried the 5&5 Rule again and doggedly kept it, via multiple spoiler reductions to go with some three Darby-mandated swaybar changes and resultant changes by Goodyear to tires - and it all accomplished nothing. The COT then debuted in 2007 as a low downforce concept - and failed.
Drivers lauded NASCAR after the races at Kentucky and Darlington because they ran low downforce - yet passing didn't improve. Neither race stood out for anything - Kentucky didn't approach any kind of record for lead changes in 2015 - it had thirteen official and nine unofficial; in 2011 it had twenty official. Darlington saw 24 lead changes in 2015, not exactly a significant upgrade over the 21 lead changes of 2011's running with high downforce or even 2014's running that saw 22.
And criticism of the high downforce package used at Indianapolis and Michigan in the summer of 2015 ignored the real problems with passing - the cars still have too much horsepower (by well over 300) and the tire used simply isn't sufficient for grip; the fact the cars never stalled out in traffic as opposed to with low downforce ought to be recognized as a manifest positive. Contrast this with the Truck series and the epic Kasey Kahne-Erik Jones sidedraft battle in 2015 with a tire that gripped well enough that they could lean hard and fight thusly - it raced more like old bias-plies than radials, notorious for needing to catch the car instead of race it. The Trucks are also high downforce vehicles.
What remains the truth is that underpowered and overgripped racecars have produced the most lead changes, be it Indycar or Indy Lights on the superovals, the NASCAR Modifieds at New Hampshire, the Trucks on big tracks, and in restrictor plate racing - the 80 lead changes at the Cal Indy 500 at Fontana would not have been possible with lower downforce; neither would the Erik Jones-Kasey Kahne shootout last May.
Making the same mistakes made in 1998, 2004, and beyond won't make the racing better, and NASCAR needs to know better - still. Racing is about lead changes, not throttle control. It's about not having to catch a racecar, not about struggling to handle.
A superb insight is provided in a question asked by veteran NASCAR writer Mike Mulhern - what is the over-under on the first rule change for 2016?