I think he meant that you know that Johny is frost mage, while Amanda is disc priest or Mark is this awesome fury Warrior. And I have to agree this is quite important to actual character/player identity. I remember, when you knew people names and what they are playing. Not just shaman, but Elemental Shaman for example. This should stay in the game how it was.
And I know hardcore raiders were switching specs often but this community was really small, didn't had big impact overal - most people were known by their specs.