Well Chuck, good to see your getting the point.
If you have a 7 bore, another stays home. There are 20 or 30 calibers between say 25 and 30 that can do what the 6.5 can do. Some are very close, even across a bore or two. Does a 270 have any .....on game...difference to 264wm.
I have had spirited discussions with Gatehouse over his 375 Ruger vs my 375 Rum. If you have one, it's unlikely your going to change to the other. We all have our justifications, history, and biases.
I have some old calibers, some obsolete, some new. My 6.5 has always been the 264wm; actually if I was ever to change my user name, it would be Magnum 2.5. My particular bias is the 2.5" magnum family.
However, I'm not close to consistent. To justify bulging safes, different firearms became special purpose items. My south province walking rifle is a T3 30-06, for the peace it's my Rem 700 lss in 375 Rum. I suspect many people who want a target specific rifle that don't reload, buy a 6.5cm. I do load, so pick the 264 as my 6.5.
One last thought, reloading is becoming more and more necessary. For me, the Kanadian peso, and where I live. I buy and ship a lot of reloading brass and projectile, my principal reason for being on CGN.