[gghhzzgghhzz]

well in the case of a system migration for consumer data; in many cases the developers may have moved on or even retired. In some cases operational data can have lived through pre RDBMS systems, migrations to RDBMS, migrations to different system software from different vendors, adhoc imports of data from other systems, bulk zero day currency conversions (to the Euro), different approaches for configuration of obscure product codes, bugs, systems that didn't understand leap years, developers and systems who didn't understand normalisation or timezones or decimal data types or rounding errors or character sets, crashes, 'manual' rollbacks and hacks to reset large batch jobs.

of course the value to the business of much of this data is highly questionable, but this isn't always an argument you win..