Because not caring how FP values are stored and what the implications are (or even not realising that you favorite programming language uses FP by default) is a particularly fast way to become the "minus 10 times programmer".
Storing monetary values as FP is one thing, but I've seen phone numbers and other numeric identifiers (long time ago before PCI-DSS even credit card numbers) stored as FP values, with predictable results.
Storing monetary values as FP is one thing, but I've seen phone numbers and other numeric identifiers (long time ago before PCI-DSS even credit card numbers) stored as FP values, with predictable results.