A lot of these discussions are way over my head. That said, can someone explain why they don't offer lighter bullets off the shelf for a 6.5? I don't handload. But, one thing I enjoy about my .243 was I could buy 55 grain off the shelf that were pushing 4000+ fps. They grouped well and were relatively flat out to 400 with a 200 yd zero. Which was very handy when I used to varmint hunt a lot. I think the lightest available for my 6.5 is 125.
The reason for no lightweight "varmint" projectiles has to do with how the Creedmoor family of cartridges has been launched, marketed, and sold. They're billed as turnkey, long-range, factory rifle/ammo, low-recoil solutions for the non-reloader. The whole CreedMoor family is essentially the same brass case as the 22-250 with a little less case taper to add a little more case capacity (IE velocity).
The 243Win has always been a "crossover" cartridge, marketed to be suitable for both varmints and big-game. Makes sense to offer a light/fast projectile in a "varmint" marketed cartridge.
You probably won't see many if any 55gn or less projectiles in factory ammo for the 22CreedMoor either, that niche is overflowing with choices. They're looking for the fast-twist high-BC crowd, not the 4K FPS crowd.
The folks manufacturing and marketing rifles/ammo in the Creedmoor family seem to be walking lock-step in not trying to make the family something that it's not, nor trying to fill a space that's been loaded to overflowing for decades.