What the typical programmer doesn't even realize is that this is an artifact of Von-Neumann architectures (and their assembler language) and optimization of ear

What the typical programmer doesn't even realize is that this is an artifact of Von-Neumann architectures (and their assembler language) and optimization of early compilers, not a essential property of computation. Spreadsheets, expression-rewriting languages or any other functional programming language don't necessarily have this limitation, and declarations can be made in any order if the compiler supports it.