My rule of thumb:
When you stop thinking of your character in terms of balanced strengths and weaknesses, and start thinking them of terms of "So if someone does this, how can my character come out unscathed?", then you've gone too far.
EDIT: I have a current, active RP character (not in FF14), that's gone this route, but they're supposed to be a villain that the heroes are supposed to defeat, so I let it slide a little.
When you stop thinking of your character in terms of balanced strengths and weaknesses, and start thinking them of terms of "So if someone does this, how can my character come out unscathed?", then you've gone too far.
EDIT: I have a current, active RP character (not in FF14), that's gone this route, but they're supposed to be a villain that the heroes are supposed to defeat, so I let it slide a little.
