For precision rifle competition, the 6 creed has absolutely overshadowed the 6.5 version. But in no other arena has it done so - and precision rifle competitors are only the tiniest subset of rifle buyers. The casual long range plinker guy doesn’t want a 1500rnd barrel life, and doesn’t want a round with only a handful of factory loads. The typical deer hunter, historically, has opted for rounds running bullets heavier than 105-115grns.
The 6 creed is a race car designed for a very specific purpose. It’s not a versatile everyman’s cartridge that the 6.5 Creed has proven itself to be.
I don’t care for the 6.5 creed, but credit where it’s due. Political scares pushed AR-15 sales, and shooters quickly realized the limitations of the AR-15. Some manufacturers pushed AR-10’s as the solution for the limited range of the 2.26” mag box rifles, but shooters realized the price increase and performance for the task wasn’t in line with the desire. Enter the PRS and Hornady with the 6.5 Creed. Cheap and available ammo, cheap and available rifles, long barrel life, low recoil, long range capable, game hunting capable, and at a time when the market wanted all of those things.