You're absolutely right that assumption was implicit. The answer was written totally in that framework. I'm not here to say what's right or wrong in determining something about people who lie outside of normal in these things, or what normal means.

So what I wrote should be read with a "if it is held to be a condition which deserved remediation or avoidance of it's manifestation" attached.

Most medical conditions are couched in this sense, that a deficit or departure from the normal is a problem. In matters of brain chemistry it pays to be more nuanced.