GP and I aren't talking about subjective realities merely on the level of "this is my perspective of this person and that thing". Insofar as you or I could be said to be conscious, to perceive the world and to think about it, that is the extent of our respective subjective realities. It's not that the universe exists for every single human. Rather, as humans, we each perceive the universe, and others, in the ways that we do. We could be in the Matrix right now. The nature of a subjective reality is that, in a sense, there is no difference to us whether we are "real" or in the Matrix. What we perceive is what we perceive. How useful this model is is a different matter, but it's not solipsistic.