Hes being an ass about it, but I "think" hes simply saying that everything, at face value, can be replaced in the next expansion.
Everything can, and probably should. If no items from expansion N has an upgrade in N+1, then what's the point?
(save, of course, for new content to see. Before you head back to old zones)
The problem is, of course, what replaces what. And it requires tiers of content. Like: Leveling - Endgame Solo - Group - Easy raid - Hard raid. Well, EQ didn't really had the first two, because you were not considered to be able to solo anything meaningful. So, let's collate that into "Leveling group - Endgame group".
Nobody has a problem that endgame group of N+1 is equivalent or sometimes replaces easy raid of N. The problem we have is when leveling content drops stuff that is equivalent or replaces hard raid content. And no, Kunark did not do that. At best, you might have had group content in level 60 zones that was close, or just above PoH/PoF items. None of those ever replaced PoS items.
Even the Kunark->Velious transition, which was harsh, did not approach close to the modern WoW where solo leveling content replaces easy raid content, and endgame solo replaces hard raid gear. Well, WoW is at the point where solo endgame content replaced group content IN THE SAME tier (WQ stuff being higher ilvl than heroic gear if you had enough ilvl average).
So no. The idea that EQ had "gear resets" is ludicrous.