We have conceptualized machines generally, and computers specifically, as simplified models of the body and the mind, and then reversed the metaphors so that machines became how we view our bodies, and computers have become how we view our minds, with all the limits attendant upon that. The metaphors become more impoverished with each switch. This is a central concern of what we term the Self, and how we envision its possibilities. Just because we can only (so far) build things that mimic aspects of us, does not mean we are comprised of only those aspects. Just because we see ourselves in a mirror does not mean we are two-dimensional and live under glass.
If we're modelling our thinking about the mind on the computer, we need a richer wider view of the thing.