Perl was the #3 language on the Tiobe ranking in 2005. It had massive codebases in banks and other industries. In 2019 it was ranked #19 and the incompatible replacement, Perl6, is #93. Breaking backwards compatibility is hugely costly. It creates immense work as people have to validate that new versions of previously working code meet the implicit, accumulated requirements.

Old code will always seem old fashioned. It will not address modern concerns. However, the option to keep using it is very valuable!