While I go back and forth on that point -- lots of people will just gear a toon for its own sake without necessarily planning to raid on it -- I don't think she's entirely wrong, and I also think the larger point concerning the Dungeon Finder's potential impact on server communities is probably accurate.
It's no secret that I love running 5-mans, and queuing up for the Dungeon Finder has added another layer of fun to the process. But one of the things that's eaten at me lately is that I've spent increasingly less time hanging around Dalaran watching for the players advertising for a tank or healer. I don't need to do it anymore; I can get a 5-man from anywhere without having to watch trade chat. As a player on a low-to-medium pop realm, the odds of my being grouped with anyone from my server through the Dungeon Finder are pretty low. The result has been that I've spent very little time tanking or healing for people from my server who aren't already guildies.
That bothers me. Pre-3.3, If I met a particularly good player in 5-mans, I'd mentally bookmark them for later in the event that they applied to my guild. On the flip side, if someone was a real jerk, I'd also file that away in order to avoid them in the future. Doing 5-mans with other people from your server is a great way to keep your thumb on the latest gossip, trade news about how your guilds are doing, and establish relationships that may resurface later. While you can certainly convene server-only groups with the Dungeon Finder, it's significantly slower, at least for a tank or healer. Queue, boom -- three seconds later you've got a free dungeon port.
I absolutely adore the Dungeon Finder and I wouldn't give it up for anything (seriously, patch 3.3; great patch or greatest patch?), but I do wonder if: a). the sheer convenience of the thing will eventually have some sort of impact on server communities, and: b). if the increasing array of geared toons will spur people to start raid teams on their own servers, or to look farther afield.