Kind of black and white view. Unless music is just compositions on paper to you. You can totally have soulful, emotionally transcending music rid of any keys or scales whatsoever. You can't, however, create interesting music with all the theory in the world, if there is no soul. I know cos I've done one album chromatic and one in minor keys (minus one song), albeit the creativity level was the same so the keys did make it feel more coherent. Still, I find the price is the extra difficulty in making it fit within scale, sometimes in lead melody pitches and fitting melody lines in bars with time signature, but mostly when it comes to making 2nd guitar backing stuff like power chords, and especially if you want to harmonize the lead melody with a constant interval, but can't as you have to evade accidentals unless you want to use a clusterfuck of passing tones. Thing is, some use theory laws to make it easier (or musically safer), but making it easier without sacrificing the nuances of mood is tough.
Then what makes it 'work'? The abstract laws of tension and resolution? It seems very vague to me (at least hard to grasp), which gives musical freedom, as it's fundamentally spiritual, otherwise we could have computers create interesting music. The whole thing of tone X wanting to resolve into tone Y is something that should be felt, cos when going by the book all the music becomes the same. (I'm not on the level of understanding or utilizing this much in theory, tho.) This of course applies less in genres like black metal where you intentionally have more dissonance and tension than usual to create suspense and restlessness, to the point where release must be done tastefully to avoid a feeling of warmth, hope and satisfaction, instead creating other sorts of feelings and mental imagery.
You can argue, but if there's something to suggest what direction I should look into next then do point the way. Honestly I have no clue what to learn next, maybe harmony stuff, there's some cue how to build good harmonies, but it still seems to come only thru trial and error, especially when there's more than two notes being played.
