I'm not sure if that's what the (almost certainly delusional) linked article was talking about but your explanation holds water... but only for onboard motherboard embedded audio. That does tend to pick up a lot of electrical noise and just be mediocre at best.
However this can all be sidestepped with an affordable external DAC connected with optical or USB.
That sounds like some kind of ground loop problem, then, maybe?
There are battery-powered USB DAC/amp combos, primarily designed for portable use. I think FiiO makes/made some. That should solve or at least isolate the problem further to some extent.
However this can all be sidestepped with an affordable external DAC connected with optical or USB.