You're right that they do differentiate in those ways, but my point was that they never overtly explained the purpose, or attempted to make logical connections where possible.
That, and there's a lot of toe-stepping with regards to 'uniqueness'. Best example is that of fighters only ability being fighting, but so can cavaliers, paladins, barbarians, rangers, etc and they all got special abilities on top of that. So what's 'unique' about a fighter?
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