So I'm probably missing something

[Tedronai]

Consider: shouldn't someone's aspects actually guide how they intend to play their character?  Isn't that the whole point?

Yes, and when doing so represents a disadvantage, they're to be compensated for the (self-/)compel with a FP.

[Sanctaphrax]

What Tedronai said.

Ideally, the player would never have the opportunity to try the subtle spells. The GM would compel him as soon as it becomes clear that a subtle spell would be helpful in any given situation.

[CottbusFiles]

What Tedronai said.

Ideally, the player would never have the opportunity to try the subtle spells. The GM would compel him as soon as it becomes clear that a subtle spell would be helpful in any given situation.

This is right. It's hard to do at first but in my opinion FATE works that way. Compel as much as you can  the Story will write itself

Edit:

I agree there, but what I meant was someone choosing aspects that specifically counter the way they intend to play their character in order to farm FP that way.  If their aspects are geared toward thuggish spells, and the player always tries subtle spells first (tugging out the compels) they get a free-flowing source of fate points at no real disadvantage-- they're doing it intentionally.

Consider: shouldn't someone's aspects actually guide how they intend to play their character?  Isn't that the whole point?

Aspects guide how you get and spend FATE Points. They help you a lot in how to play your character but mostly they are there to let you interact with FATE Points. This is a really gamist concept but it works really well.

[sinker]

My 2 cents, for mental stress dealing illusion I would require the same thing that mortals need to deal mental stress to each other: Intimate knowledge of the target, or special training in torture.