I can't speak for all of them, but in Ableton it's entirely possible to create a feedback loop. Although you'd have to be pretty dumb to actually get it that far. You'd have to route track A to track B, then route track B to track A, AND make it so that one of them sends to the master out, AND turn on input monitoring for both tracks. In practice, this'll (virtually) never happen, and it's quite a useful function to have.