I hate it, but, it's not at all against ToS.

Technically, it's not much different from me taking newbie FC members into content I've cleared. They get a faster queue and clear, I get newbie bonuses and a WT reroll point.

But, it just comes off a bit skeevier since you advertise content carries and players a can make millions doing it.

There was also an underlying concern with this in ARR days (where selling clears was EVERYWHERE) that it encouraged RMT buying since players who, for one reason or another, couldn't complete content suddenly had something the felt obligated to spend mass gil on. So, they bought gil and bought the win.