I agree! It seems super difficult to figure out whether a movie (or literally any media) is financially successful now. But I don't think that's a good reason

I agree! It seems super difficult to figure out whether a movie (or literally any media) is financially successful now. But I don't think that's a good reason to give credence to a metric that strikes me as being incredibly obsolete. A bad metric is a bad metric even if it's unclear what metric to replace it with.