What they are confusing this with is their preference for an
intentionally flawed but
entirely pleasnt and relatively benign form of distortion. Nothing
wrong with their
listening preference but the presentation of this as inherently
superior is utterly
bogus.

The idea that valves are simply "added distortion" and nothing else
could only be made by somebody with a) very little knowledge of modern
valve circuits and how they sound or b) somebody with cloth ears.