I mean, I get the idea of using an "average score" or whatever. But there's a problem with that.
Consider your two hypothetical golfers from earlier.
I think we'd both agree Player B is the better player, because he consistently shoots solid scores. Player A sometimes shoots a great score - lower than Player B can pull off - but often shoots mediocre or even bad ones.
So let's say we count more scores in a player's handicap - let's count all of them, just to go to a logical extreme and illustrate the point.
Player A's average score is a little over 81. Let's assume a course with a rating of 72/113 for simplicity's sake. That makes him a 9.6 or so.
Player B's average score is 77.95. So he's a 5.95. Which makes sense so far - he's the better player.
But as the better player, he's screwed. Because anytime he enters a full-field competition, he's always going to run into a bunch of Player As. And some of those Player As will blow up and shoot 90, sure. But some of them are going to shoot that occasional 73. And when they do, they're firing a -8 round.
For Player B to fire a -8, he'd have to shoot 69 or 70. And he just plain isn't capable of doing that. He's a good player, and a consistent one. And he should be rewarded for that consistency. But when you start counting more and more scores, and changing a handicap from a reflection of potential to a reflection of average performance, you inevitably reward the guy whose average performance involves a lot of inconsistency.
Which, I would say, is exactly the OPPOSITE of what a handicap system should do.
To me, one of the joys of being a handicap golfer is that you have two incentives: you're rewarded with a lower handicap as you play better (which I think most of us consider a reward, even if it raises the standard by which we must perform to win), and you're also rewarded if you consistently play somewhere near your level of ability. Consistency allows you to win more matches and contend in more events or games, even on days when you're not on your A-game.
To me, it's a no-brainer that a system based on potential is far superior to one based on average, even though I know it sucks when you're in a slump or injured and that cap seems like it takes forever to rise.