Rewarding consistently better performing players with successively better gear would be game-breaking, period. If the system were designed to give better players better loot, lesser players would call behind and not be able to catch up. "Fair" doesn't necessarily define a context but in PVP game design, I'd expect it to translate to making the game competitive. To that end, equalizing lesser players with better players could be said to be "fair" in a pretty strong sense. In many ways, that's what the notion of fairness has become: a penalty to the strong to benefit the weak. The other way to make it "fair" is to see that everybody has the same equipment so that scores can be a more objective measure of performance. Both avenues would severely alienate users. That leaves us with random lottery. Loot gets passed out and is distributed with no bias. Some players get better gear than others but this doesn't necessarily stratify the user base. It's the only way to go.