In my view it’s because democracy is somewhat orthogonal to capitalism or collectivism, and masses are easily controlled anyway (they can live with the illusion of being in control). A democracy loses something central to the concept when a restricted group has a very concentrated power (be it political, as in the case of pure collectivism, or economic, as with pure capitalism). In my opinion there can’t be true democracy when there are strong imbalances in a society, even when there are regular democratic elections.