I was, to put it mildly, skeptical and it was a year before I decided to give it a try. Now, I'm a convert.
For me, a 30 second to 1 minute flush with very warm water, followed immediately with wiping down the chamber with wadded paper toweling and pipe cleaners produces a fresher tasting bowl than using any sort of spirit. It helps neutralize the bowl. But many pipe smokers don't want a neutral bowl, they want it either seasoned with a favored blend, or flavored with spirits, or honey or something else.
Unlike some who do this, I don't leave a vulcanite stem attached as the warm water can raise the sulphur content and cause the stem to go gray, so I treat the stem separately with alcohol. Acrylic stems get a warm water flush as alcohol is deadly for acrylic stems.
Also, a couple bowls may swell a bit and may need an extra 30 minutes to an hour before the mortise fit returns to normal, but that is pretty rare, and the fit always returns to normal. Briar characteristics vary from bowl to bowl to bowl.
Any pipe that I use in regular rotation gets this treatment and none have suffered from it.