Why do people [airline apologists?] keep going on about the CoC as if they were the Ten Commandments that Moses received? They are just some rules that one or more airlines dreamed up, no more, no less.

Almost all of the comparable examples posted in this thread (and many others) are perfectly relevant, if the service supplier dreamed up a similar set of T&Cs.

I have a shop that sells beach toys. I have a rule that customers must buy things exactly as they are in the shop, and must take the entirety of their purchase with them, off my property.

A man comes in and wants to buy a bucket. I sell them for $5. I also sell a combination of bucket, shovel, and tractor in a fishnet bag for $4 (my Chinese supplier sends them to me like this.)

The man says "How strange, you're willing to give me more for less. Oh well, I just want the bucket, my son already has a shovel and a tractor, so why don't you keep those, sell them to someone else for $2, and I'll give you the full $4 just for the bucket."

I say "I can't do that, it goes against my terms and conditions."

"But that's stupid. Everyone's a winner if we do what I suggest. You get $6, more than you would under any other scenario."

"Sorry, but them's the rules. Either buy the bucket for $5 or the combination bag for $4."

"OK, but I will throw out the other two things as soon as I get out of the shop."

"You are not allowed to do that. Make sure you take them off my property."

It is the same thing.

As I have said before, if you were to start airfare rules from a blank sheet today, you would never get into the idiocy that exists today.