I bet you're right. I'm learning Spanish but not studying so much of the grammar literature, so I was just trying to figure out the justification for it. But that being said, is there a difference in meaning between '-me' and 'a mí'?

I guess for me it's just frustrating to think of it in terms of case since I speak German and the case system in Spanish barely seems to exist in comparison, when the only things that meaningfully respond are third person clitic pronouns and almost no dictionary even marks the valence of verbs, rather just indicating algo or alguien and common preposition pairings. It seems like talking about the genitive in English -- just a preposition 'of' and '-s'. At that point, only linguists might ever care to think about it in terms of case.