[kwhitefoot]

Perhaps not super simple but it will have been broken down into named parts. In the days before spreadsheets were as capable as they are now I worked with plenty of quite old engineers who would write Fortran instead; their Fortran was always better than the spreadsheets that they later produced.

[listenallyall]

The degree something is well-designed and comprehensible is based mostly on the developer, not the tool. A spreadsheet with named ranges/tables, cell comments (sparsely, where necessary), clearly-defined tabs, etc can make debugging or reverse-engineering a breeze. The visual aspect of Excel can also help debugging immensely, i.e. conditional formatting of cells failing validation, filtering to isolate subsets of data, etc.

I will certainly agree that it is quite rare to come across a spreadsheet that is perfectly-organized, on the other hand a ton of developers write horrible spaghetti-code too. Further, a 10+ year-old spreadsheet will open right up in Excel... while a 10+ year-old data project is often written in a language you've never used before (or hoped you'd never use again).