[erichocean]

But the memory model with which they are coupled is just as important (I have in mind the grid addressing system and dataflow semantics)

Totally agree. My startup is using hierarchical grids as our core datatypes for just that reason (we also support Function cells that are used as values).

"Naming" is one of the core problems in computer science, and grids/spreadsheets elegantly solve that problem for many ad hoc use cases, where functional programming (in all its forms) does not.