Let me see if I can address the ideas of advocating for characters more directly, and maybe also the idea of the GM playing adversity without having to pay for it.
The introduction of the compel shouldn't necessarily trump the resolution of a conflict by other mechanics. In the particular problem case that we've been discussing, the compel can best be used as a way to get the GM and players to discuss how to make the conflict a more interesting part of the story. The GM brings the adversity, in the form of antagonistic NPCs and environment. The Compel gives the GM more latitude to turn the screws that much tighter, because the PC has a connection with this particular adversary. If the characters Aspect(s) suggest a way in which the conflict would be more interesting, by upping the stakes, or complicating the possible consequences, or changing the arena, he can suggest that the story take that particular turn, and offer the player a reward for giving him the tool to take the story in that direction.
Assuming the PC accepts the compel, he still gets to advocate for his character, but he might be up against tougher odds, or he might have to accept some limitation while doing his fighting, or he might have to concede a setback on one front so that he can concentrate on another. Hopefully, the upshot is to increase the drama at the table, either by the increased risk of failure, or the pathos of having to sacrifice one desire to pursue another.
I don't know if that was very clear or helpful. Usually I include examples to supplement these sorts of discussions, but I wanted to try to address things in general terms in this case.
P.S. Sometimes it is a good idea to let the compel short-circut the other game mechanics, if the consensus at the table is that the process of determining the some outcome won't be much fun, and there's one particular outcome that people are excited to see. In that case, a compel, accepted or bought off, could the the most agreeable and efficient way to get to the good stuff. But I think we're concerned with conflicts you want get more fun out of, rather than the boring ones you might want to skip.