That seems like a pretty uninformed hypothesis. For example, halting oracles can process symbols, but are not computable. So, maybe it is necessary, but easy

That seems like a pretty uninformed hypothesis. For example, halting oracles can process symbols, but are not computable. So, maybe it is necessary, but easy to show symbol processing may not be sufficient (as I just did). This has significant implications for the engineering discipline. For example, if the mind is a halting oracle, then you can get much more performant algorithms by incorporating human interaction.