Brain as a computer, in my opinion should be the default state for this discussions. Why? Consider the old and tired brain-made-of-matter argument. There's no reason to think there's something magical or supernatural inside the brain, so treat it as an organized collection of atoms doing cool stuff. The default state cannot be magic, it has to be something that can be disproved or ruled out.
Some parts of it seem to work, as fas as we know, in a (suspiciously) algorithmic way, or in other words, a highly abstract step-by-step chain of actions can be identify for a given part of the brain.
Why not start with the crazy assumption that the whole brain acts as a computer (the theoretical concept), and then identify which parts of it fail the analogy? The key part here is the word 'fail': it should not mean 'too complex for any computer we have built' nor 'we don't know any algorithm that does that', it should mean that there are parts that inherently cannot be modelled, under any circumstances, like the definition of algorithm. If some part is discovered not to hold the analogy, you should just then question if the analogy is question is apt or not.
