OP, I think for the most part your assessment is true. However, one thing you should also keep in mind is that most people play video game for a particular type of experience. The want action, they want to duke it it out. They want to hit the trenches and chuck 'nades. Sure, if they wanted to treat it like a serious job they could camp in a dark corner with the shotgun (not saying that's what all 50's do) and go +5. Most players are more focused on "How" they play the game vs. the final score. I do think there is still a pure skill gap in weapon use, nade accuracy, etc. If what you're saying is true then a 50 vs a 40 in a empty room with nothing but BR and 2 nades per spawn should have a close score. But we know if most cases the 50 would do better and it won't have anything to do with teamwork or common sense.
I am, however, curious how the arena ranking system in Reach will effect rankings since you're more likely to get a higher score with a worse team (you'll get a larger chunk of the kills/assists). Hugs & Kisses.
[Edited on 09.10.2010 11:44 AM PDT]