Using newer Excel you also have the power of making custom named functions with LAMBDA() which can also recurse (I think the stack limit is 1024). If you combine this with the idea of columns or rows as iterations of the memory with some of the array functions like MAKEARRAY() and relative position functions like OFFSET() or INDIRECT() you can do pretty much any reasonably sized computation without needing iterative calculation enabled.

The reason being Excel is a tool designed for performing operations on tabular data not designed for general data programming. If you needed programming there was always VBA which was proper so they never wanted to muck it up. LAMBDA made its way in because people wanted reusable function compositions for their tabular data without having to enable the security PITA that is allowing full macros/VBA which can do a lot more than interact with just the data inside the spreadsheet.