Inspired by comments below and the 6N in general.
Let's say a player has been tackled, places the ball well out the back of
the ruck, ruck has formed, competed and died out with several players from
each team in the "pile" and the scrum-half is standing over the ball waiting
to play it. Basically, everything has stopped.
What, then, is the point of a defending player running headlong into the
ruck with a big hit on a player who is already pretty pinned, and ending up
on the floor or tangled up? Is it like deer butting each other with antlers
to see who's the boss or does it have any kind of tactical advantage? From
what I can see (and I saw it plenty of times during the 6N) you're pretty
much taking yourself out of the defensive line, just to give a whack to an
opponent who is usually already out of the game if the scrum half was to
play the ball there and then. I could be wrong but I'd have thought that
having the maximum number of players on their feet when defending would be
the most advantageous way to play? I can see why the attacking team does it
(to take a defender out of the next play) but I don't understand why a
defender would. Red mist? Revenge for an earlier bit of naughtiness? Or just
a free hit?