Not saying they invented it.

The wiki article states that they are an expression of attitude and modality.

The Aus gov style guide states the mood conveys meaning.

The top-down imposition of meaning via a mood, forces the intent of the speaker into the listener, simply because they have that mood.

Leaving a grammatical mood as an attitude of the speaker, is much more desirable. Relating to grammatical moods as an attitude leaves open the door to possible changes in the relationship.

Moods conveying meaning, does not.