The point he was making is that traditionally cutting edge raid encounters are designed around players having access to certain abilities. Just look at the clusterfuck surrounding Nyalotha. The top guilds were spending millions of gold, clearing out the AH for corruptions in order to beat the Mythic encounters. That is the world he plays in. The vast majority of us, if we get to stand in front of Mythic N'Zoth will over gear the encounter (and still struggle).
I can understand his frustration when a few % of a DPS upgrade is the difference between beating the boss and failing.
Personally, I'm excited for Shadowlands. It feels like its going to be a proper RPG again.