I'm going to attempt to explain my position and, as best I can, explain why your position on this matter fails for a plethora of reasons. First, you're making way too many assumptions. In your world, the one any only fact that matters is achieving maximum velocity which you quantify as performance. If everyone adhered to your analysis, there'd be only 3-4 different cartridges in the world. The 3-4 to four different categories of cartridges would be filled with what would be considered the best performing cartridge. The 30-30 Winchester would never have become the most widely used deer rifle in America because of its less than stellar ballistics. Baskin Robbins Ice Cream serves a 101 different ice creams. The reason is simple, people's choice of ice cream is based upon 1001 different preferences. The same applies to rifles. Peoples choice of a rifle cartridge involves a number of factors, not just velocity or performance. Like the endearing 30-30 Winchester, many people chose it because they liked a level action or, they chose it because that's what their father and grandfather shot. Today, thousands are opting for the 6.5 Creedmoor because it's the latest fad, not because its the best performing cartridge available.
I chose the 6.5-300 for several reasons. At present, I've got 9-10 different bullets in 6.5 in varying weights sitting on the shelf ready to be tested in a 6.5-300. I don't have any 7mm bullets as I don't own a 7mm rifle. I have no desire to start another collection of bullets. Also research indicates that the 300 Weatherby (which you suggested I stay with) has approximately 34 pounds of felt recoil; the 6.5-300 is listed at 20 pounds of recoil. I crushed my spine, twice; three fused discs, a titanium plate and a dozen screws in my spine are the result. I don't do well with heavy recoil. That's why I'm opting for a muzzle brake as well. Also, I was around 19 at the time, fifty years ago as you assumed I wasn't around. It's when I purchased the 300 Weatherby. Additionally, your statement,
The statement is misleading at best. To claim that 100% (all) of the 6.5-300 owners switched over to 7mm is a complete fabrication. Many may have, to claim 100% changed over to 7mm is baseless, it simply assuages your mindset. There are no facts, records or writings to support your assertion. It reminds me of the nonsensical statement made by Trump last week claiming he won (all) fifty states in the 2020 election. To suggest that a majority of left wing radical California and New York State citizens would vote GOP, let alone for Trump in today's political climate, you've got to be a megalomaniac.
The 7mm-300 is a great cartridge, so is the 6.5-300. I was surprised by the number of LRH members that also shoot the 6.5-300 and embrace it. The fact that the 7mm-300 might edge out the 6.5-300 by a few feet in velocity is meaningless to me. Other factors including just personal preference outweigh this fact. It's the Baskin-Robbins preference I've made.