As a semi-retired long range target shooter, I can attest the biggest reason for paper punchers using 6 and 6.5 calibers is not anything other than recoil. A regional Match normally consists of 80 round ( 4ea 20X600) or 45 round ( 1 ea 15 X 800, 900, 1000) plus sighters. most match shooters prefer to put bullets into the X ring, not energy into the berm/and shoulder- it make Xs that much harder.
Me, I still break out the NM M1 with heavy loads of 190s for anything past 600....
30 cal bullets indeed do provide great BCs, but at a cost of recoil and bigger cartridge lengths with allsorts of associated issues. Have you seen a 240 SMK or Berger? They’re is long enough to put an ink cartridge in and use as a pen... BC G1 in the 700+ range, but as you state, you can do that with a Hornady 140 grain ELD 6.5 and about 25 grains less powder and recoil exponentially lower. Paper doesn’t resist much though.
I really like 30 cal rifles. I have a 30-40 Krag, 30-06’s in 1917, 1903A3, M1 Garand and 7.62X51 in Springfield M1A. Not including non mil rifles in these calibers.