I learned Perl in the mid 2000s because I was working with a company that took text (and sometimes spreadsheet) dumps of public records data and processed them into a database. The entire ETL pipeline was a set of Perl scripts, and, as far as I know, that system is still running. The Perl iteration was actually the second iteration of that system - the first iteration was a set of C programs and shell scripts that were replaced over time.

The rich ecosystem of tested Perl modules for file formats along with the testing frameworks made coping with change bearable - not enjoyable, but bearable.