To the OP, there is nothing wrong with the selling of endgame content for an in game currency since it is an amazing way for a guild who has the capacity to carry others the ability to fund their materia/repairs for the gear and content to come.
Personally I've sold heroic raid kills in WoW in guilds I've been in and we did just that we used the gold we earned via selling runs to fund the whole guild's flasks, gems, enchants and food for the current and following raid tiers.

Quote Originally Posted by Ladon View Post
I'm pretty sure gilsellers aren't running people through the end-game fights.
You'd be quite surprised actually... One of the best ways to gain mass amounts of gold is by selling endgame content runs and if you look at WoW you'll get quite a few Asian based guilds on most NA/Oceanic servers advertising in trade selling heroic content and pvp carries for ingame gold or real world currency.