I agree completely. The problem is the human factor which includes but is not limited to self-fulfilling prophecies. When I threw the Flow it had tremendous, almost easy glide, but it was incredibly nose sensitive and did not like being powered up. When I throw the Sword it can take some error in my throw and still remain relatively true to my target. It was also not as sensitive to nose angle, although I will concede that if you do not hit it just right, it appears to lose all glide and come up well short of what I know it is capable of getting.
When I purchased my Flows, I was expecting a long River and threw it as such. It performed admirably when powered down but did not respond well to being powered up, just like my Rivers. When I purchased my Swords, I was doing so with the intention that they would fly like my TeeBirds. For the most part, they did. Hence, when they flew for the first time they flew exactly how I expected them to. This obviously plays a huge factor into how I compared the above discs.
However to all this, the Boatmans I picked out flew nothing like what I was expecting. Considering its listed numbers of 0 turn and 2 fade, I was expecting a very TeeBird like disc, a fairway version of my Swords, but they meathooked instantly out of my hands. So I guess expectations cannot always make a disc fly how you expect them to.
So, a dash of millimeter here, maybe a subtraction of a millimeter there, and a ton of personal experience mixed in with high expectations, and poof, statistically similar discs fly nothing like each other. At least that is the story I am sticking to for why my observations differ from everyone elses.