[akhtene]

Don't you forget that there was war going on in the North too. Lorien, Mirkwood and Dale were attacked. Luckily Rivendel wasn't, but could Elrond leave his realm at such a time? So the defence of Minas Tirith was purely Men's job (not to mention the Companions). And I think that by that time Elrond's sons had already decided to stay in M-E with mortals, so the war in the South was their war too.