I'm not sure the distinction between logical discourse and life advice is a useful one to draw. The reason that ad hominem is considered harmful is it leads to dismissing ideas without considering their merit.
Dismissing advice out of hand purely based off of the source seems like a dangerous shortcut to espouse, as it's likely to lead to groupthink and echo chambers. I think, when looking for advice, one should go out of ones way to solicit different backgrounds (dare I say, a diverse set of opinions) and then synthesize them into a course of action.