It’s one thing to run a friend through a dungeon that might be a little too rough for them because you’re a Cool Pal. It’s something else entirely to do it for a rando and ask for real money in return. In World of Warcraft, the latter is unacceptable, and Blizzard’s started banning top players for it.
According to PCGamesN, it’s become fairly commonplace for the cream of the game’s crop to boost players with less time (but more money) on their hands through tough dungeons. The boost-ee gets loot and achievements, and the boost-er gets real cash. Everybody wins... sorta. Blizzard, however, says they’re done turning a blind eye to these practices.