You're absolutely right. We were just trying to illustrate what "Spreadsheet Hell" is like when you use Google Sheets as a big connected system.

Deleting a column is an illustrative example, but from what I hear from a heavy Sheets user is that it's pretty common on a shared document for people to break formulas. This is harder to notice because formulas are hidden behind selecting a cell, and harder to fix because you don't always know when it was broken to fix from history.

I'd imagine there's a wide practive of having sanity check indicators in spreadsheets. I wonder if there is tooling support for this in current products like gsheets?