But brains do, in fact, compute things!
There's no reason to think that they compute things the same way silicon "computers" do -- that they're arranged in a von Neumann architecture, or something. But it is true that they perform computation somehow, and therefore are subject to a similar set of constraints, and share similar goals (efficiency, persistence, etc) with modern silicon hardware. (Considering the differences is also insightful; ie our wetware is a much noisier environment than silicon, and likely requires a different approach to error correction.)
This is a useful perspective, for reasons that GP pointed out. We know of many different physical arrangements that are conducive to computing: e.x. Turing machines, von Neumann machines, RNNs are all Turing complete (in principle), and all look very different. So we should question our assumptions about how the brain is organized. Why should we think that, say, sadness "lives" in some physical location in the brain? Does your email "live" somewhere on your computer? (In some sense yes, in some sense, no...).
Is it not equally plausible that the brain implements a very large RNN? And if it does, should we be surprised that if we try to physically locate, say, "sadness", we might be grasping at straws? In the absence of experimental evidence (and even in the presence of it, if flawed assumptions are driving the sorts of experiments we conduct), both seem plausible to me.
Which is just a long winded way to say, I think there is some value in questioning these assumptions. (Not blindly swallowing others, just pushing on why we have the ones we do.)