You misread what I wrote. Nowhere did I say 308 was "superior" to 6.5cm. I did say it was significantly cheaper, that is a fact in today's market. I do wonder how much of 6.5cm vs 308 is marketing hype and how much is actual performance.
I decided to do a little research. Looking at the premier long distance bullet manufacturer, Horndy, is interesting. For the precision long distance ELD bullet there are seven 308 versions and eight 6.5cm versions. Overall Hornady make three times as many 308 bullets (65) compared to 6.5cm (22).
So what is the value of 6.5cm vs 308 on the range?