Theory and evidence go together. Either one absent the other is pretty useless.
Perhaps I misunderstand. Not sure what you're saying, but ponder this: If theory is assumed correct, but there is no empirical evidence to back it up, I agree that the theory was not directly helpful. (Indirectly the theory can still be useful. It isn't possible to prove every theory correct [theorem?]). Conversely, however, if practice and use reveals that something works, why does it matter what the theory says? That part does not make sense to me. If it works, it works!
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