Except the airlines use a geographic hub system, so outside of (let's generously pick a large number) a dozen large cities you do NOT have the freedom to pick f

Except the airlines use a geographic hub system, so outside of (let's generously pick a large number) a dozen large cities you do NOT have the freedom to pick from a large set of carriers that go to the places you're trying to go. Much more the case if your time sensitivities eliminate layovers. I did a ton of travel in my 20s out of Denver, where I was a United frequent flyer. In my experience they have one of the smallest seat pitches in the industry, which even though I'm 6'4" didn't matter much at the time due to the free upgrades, but when I started travelling less, I simply didn't have a lot of freedom to just go to American on a whim.