There's a new game in town, and Artirius of the Aerie Peak server has noticed it, and admittedly, so have I. With attunements gone, it is now possible for any level 70 to go in and see tier 5 and 6 content whenever they want. Of course, they don't generally have a prayer of actually downing bosses unless they have 20-24 well geared people to help them out.
That's where gold comes in. With a few thousand gold, you can buy your way into a tier 6 group that doesn't need the tier 6 armor and go along for the ride. A few hours later, you come out on the other end with Illidan dead and a few shiny new drops, even if you've never set foot in Karazhan.
It's not just people trying to buy these slots in the trade channel either. As Artirius observes, many raid groups are actively soliciting for buyers for their raid slots. On my own server, one Horde group is trading tier 6 runs for large quantities of certain herbs, promising that all but a few select drops will go to the people who buy their slots with stacks of Netherbloom and Ghost Mushrooms.
So what's causing this?