From my perspective, average LFG/PUG player behavior has historically shown that if an opportunity for degenerate behavior exists, it will happen. Game mechanics that allow for or facilitate degenerate behavior will be abused.
Even if a player chooses not to partake in said behavior, over time it becomes so commonplace that they are pressured to acquiesce for fear of being marginalized and/or ostracized (this in particular has been exacerbated by the emergence of social media, and the magnification of niche opinion).
Before personal loot, there existed the possibility that players would be pressured into giving their upgrades to others; some well intended, others not. Because this possibility was there, over time it became expectation.
Personal loot works to nullify a specific degenerate behavior by removing the possibility of peer pressure. Since there is no game mechanic to give your gear away(with exceptions), then the expectation is no longer there.
What if we were to apply the same concept to the ways players measure personal performance and the performance of others. Removing the game mechanic/API for displaying item level and damage meters would (theoretically) cease the expectation to report these numbers for access to content (such is the case for much of the LFG/PUG community).
This is a monumental change and a hard sell to be sure, but one that could increase the overall health of the game and it’s players.
Of course, this does bring up the question of “How will I know that I’m improving?”. Similar to personal loot, a personal performance indicator could be developed. A game mechanic that allows for a player to see their own growth, but could not be seen and therefore abused by others. A visual (possibly non-numerical) indicator that relays information about the player’s average damage/healing output, and improvement or deterioration of the average.
I welcome any discourse on the matter