This is only a game - it's impossible to assume the leader is going to be on 24/7. Accordingly, elders need the ability to kick people (if the leader allows them to). Most of the higher level alliance have secondary alliances, and if the leader isn't around to boot people, players from the secondary alliance have no means to rejoin the main alliance. This is especially important during the last minutes of the tournament, kicking the lower level players so the higher level players from the secondary alliance can rejoin.