Thanks for the shout-out Freebird! It’s good to see you here. 
For what it’s worth, when i completed the CDT and the triple crown in 2006 I was one day short of 21 and a half. It is very possible that there are people who are younger than me that have completed the triple crown, though probably not many.
My first trail was the AT. When I hiked it i had the exact same opinion as “hatch” regarding purity. Two long trails later and my opinion has changed completely. Purity is not just ridiculous on any long trail other than the AT, it is impossible. In 2005 we spent roughly 200 miles on snow in the Sierras. Was i following the trail? Generally… but not by AT standards. In 2006 we didn’t know where the CDT was roughly %40 of the time. Again, does that mean that i didn’t hike the trail? Come talk to me and hear my stories, and I dare you to say that. For what it’s worth, my own personal standard for myself is having a continuous line of steps from border to border. Anything more would be patently absurd. Mind you, I am not judging other’s hikes here, just my own personal standard for myself.
Please, Please, Please, if you have only done the AT, do not think you can comment on the other trails authoritatively. If you have not thru-hiked a trail, do not think you can be authoritative about the thru-hiking experience. And, please, can we all just be a little less judgmental? This is such a ridiculous thing to argue about…
Remy Levin