Having seen Excel used creatively, I think it's an exaggeration. It would make collaboration entirely impossible. I assume they have several smaller ones, with more or less - but not exactly - the same layout as it has been adapted for new use cases, and the only way to transfer records from one to the other is to manually copy and paste the info to the relevant cells, but mind the order you do it in and double check, or the Frankenstein's Macro running half the logic will crash.

I know from working in manufacturing, at least, that people like to abuse excel and try to use it as a DB client