Imagine being able to play for 8-12 hours a day, then having to target players with 3 accounts and postional awareness of the entire map, switching to go after 1 player every time they logged in. Using the fastest planes with the best cannons, and then crapping all over the players who aren't as practiced.
Just not the example of the "best" most people have in mind.
But as Shane said, people get older, people get new equipment which reduces skill a bit in the short run. People get health issues. I'd recon there were a lot of really great sticks between 2000-2010. Just look at the scores. Back then it was new and fresh and everyone wanted to be a top furballer. There were a lot of great squads back then aswell with huge #s. I think its a lot different than it is today but either way, you still have to be on your toes. Any noob can kill you once you get caught up in a fight.