Tommy, I asked the same question about why the chf are more robust when it comes to hard use and a battle gun & I also had some questions about the mandrells use and the tooling process. Hopefully, someone will share the same link as it was quite informative.
Not sure I can 100% wrap my head around the entire deal but i think it really boils down to your shooting style and buying habits. I have always tried to be a buy once, cry once money spender (when I can). If you are going to shoot 500-1000 rounds a year, I'm not sure you could really tell the difference, but you aren't talking a huge difference to get the better tube. If you run the gun hard, then buying the best bbl is the only way to go as you are going to spend a ton more in ammo.
You can actually apply your question to most of the AR's components / add ons & you just got to roll with your wallet size and make a decision based on saving to get the better upgrade or settling.
example:I really wanted an AAC or Surefire suppressor for my sbr but got a crazy deal on phantom from my class iii compadre. I could not justify paying what was over double with the budget I had at the time. I don't like the weight of the can I have but know I'll be able to swing a top shelf can down the road.
"You cannot invade the mainland United States. There would be a rifle behind each blade of grass."
Japanese Admiral Yamamoto, 1941
"A wise man's heart directs him toward the right, but a foolish man's heart directs him toward the left."