It very well could be that average hackers are more shaft specific than good players like Crossfield and his Pro buddies. I do remember watching one of those silly season (at the time) ATD competitions several years ago when Paul Azinger went into the Pro Shop and got a driver with a senior shaft.
I think his driver broke or something like that. He smoked that driver and actually bent it in his hands to show how soft the shaft was.
Experts like Tom Wishon and others have said shaft flex has more meaning with late release golfers. Early to mid release golfers not so much. Ping says it's how much someone "offends" the shaft. Crossfield says he can adjust with any shaft.
But, how do we explain all his anecdotal experiences with other golfers showing shafts have a negligible affect? Numbers don't lie. There are several You Tube videos out there showing the same results Crossfield has had.
In my experience I personally don't like (too) stiff shafts. I have had the exact same shaft work great in one driver head and not so much in another. For me my top priorities in shafts are weight and feel.
Crossfield does make a good point that there is more money to be made by selling upgrade aftermarket shafts. It's a debate that will probably never end. Like he said the guy named White was a still a disbeliever even when confronted with the numbers.