It doesn't assume it, it's syntax, you can just use it without knowing where it comes from. It's like english. You don't need knowledge in obscure proto-german

It doesn't assume it, it's syntax, you can just use it without knowing where it comes from. It's like english. You don't need knowledge in obscure proto-germanic linguistics to use articles in your sentences. But if you want to understand why we seem to randomly attach "a" before nouns— proto-germanic linguistics has the answer (probably, I just speak english I don't know where all its syntax originates).