Reason nr1: Level 80 players are better players. (I laughed)
Actually, he might have meant that in a different way than you expected. Once you level a character to 80, try going back to a zone where it levels you down to about 35. You’re going to do MUCH better than you would have done when you were actually 35. You’re going to blow things away compared to others who are actually 35 in the zone.
Also, dungeons are VERY hard. I did AC with a group of 4 level 80s, and one character in the upper 50s… and we died lots. We had all agreed that we would not have had a chance if we were all actually 35. So as long as dungeons remain the way they are now… and the level scaling continues to work the way it does… I won’t run any dungeons on any of my characters until they hit 80.
So I think that’s what he meant. I don’t think he meant that level 80s are better “players”, but that they are much more powerful when compared to lower level players… even though they are “leveled down” to the same level.