Evidence for One Shared Mind

Analytic Idealism is not merely idealism. It also is kind of a form of cosmic solipsism. It basically asserts that individual streams of consciousness are not just individual forever backwards and forwards in time; they are forms of dissociation of some shared oceanic cosmic Mind (which sort of implies that the dissociation happened at some point in the past and before that, the dissociated stream was a part of a larger non-dissociated Mind substance).

This is contrast with other idealistic schools, such as in Buddhism, where streams of consciousness stay individual and never coalesce nor derive from some shared Mind substance (although each of them individually is One Mind). [This is sort of ironic since Buddhism is seen as no-self, but since Mahayana is also anti-svabhava, the streams of consciousness apparently constitute independent "selfs" if you integrate their states in aggregate over time.]

Is there any evidence or any logical arguments for the idealism of One Shared Mind rather than individual and separated streams of consciousness co-existing and co-communicating?