It seems that Materialism and Idealism are now being described as monisms. So be it, as long as moving the terminalogical goal posts does not change the nature of the game. The plumping for one causes the other to be resorbed so to speak but not a quite vanished or banished twin. It's a position that always seem to be held 'against' the other one. Advaita is, in my view, a true monism in that there is always only a unity of being. However we do move from the 'natural' dualistic position of self and other towards it even if that 'movement' is purely notional.