I got it. I just don't necessarily agree with it. While I'm not saying the DM is the big, bad, boss, players will often see themselves as exact equals and set the DM up higher, just by virtue of his different position. In my decades of experience, players will resent another player saying something, where they wouldn't resent it or would resent it much less if the DM said something. Further, the fastest way to make someone really defensive and make sure that they aren't listening due to the defensiveness, is to confront and trap him as a group.
The DM is most often going to be the best one to speak to the disruptive player about his behavior, preferably outside of the game away from the other players.