Bullshit. It has been known for decades that it's not the serotonin levels that matter, rather, the various down/upregulation cascades that follows after elevating serotonin levels for a few weeks. We don't know the specifics, but SSRIs work for a large chunk of people. That's beyond questioning at this point.
Can you attack the root cause by means other than serotonin levels? Possibly, but that's the best we have for now.