He's suggesting developers working on an MMORPG, actually play the largest, best-selling game in the genre. It's not really a far-fetched idea. There's a ton of developers out there who don't actually play games in the market/genre they are creating for. This leads to bad design, and repetition of mistakes that others have already made and solved.
I'd be scared if a majority of the developers (at least the design team) had not played World of Warcraft. What the hell are you doing working on an MMORPG if you haven't at least academically played the genre's most iconic title?
Oh right, they didn't and look what happened. All art and design draws inspiration from other art and design. There are plenty of good things about World of Warcraft, and there are also plenty that may not resonate with the Final Fantasy audience. There's also plenty of room for original ideas.
