I think I got it now. The recommendation of stepping on the clutch would just avoid your engine to shut down.
Nevertheless I've driven manual transmission cars for more than 12 years (in Portugal less than 1% of the cars are automatic; I got my automatic 300 SL last summer) and never had this type of problem: upon reaching a complete stop I just hit the clutch.
What I understood from the conversation with my friend was that you could actually stop in a shorter distance if you step the clutch simultaneously with the brake pedal. I assumed that the modern ABS sytems could somehow be fooled by the engaged transmission, thus reducing the ABS efectiveness...