I've also used Perl for small utility programs (basically as a "enhanced" shell script). The problem with Docker or virtualenvs is that they greatly increase the installation complexity of your script.

For example, two years ago I wrote a small (50 LOC) Perl script to convert between two text format. On Unix you could install it by just putting the one file in /usr/bin. It would run in less than 1 ms, which was critical because it was repeatedly invoked by another (legacy) program. It was mostly a bunch of regex so it was natural to write it in Perl (or awk maybe but I don't know awk).

The python equivalent would have been at least 30x slower, significantly longer, less portable etc. Using docker just for this script would have been overkill. The only real alternative IMO would have been to make a statically compiled Go or Rust binary.

I do use Docker for freezing dumpster fires like CSS toolkits that need to be built using node. And that works well to a certain extent, but there is still the complexity of Docker, having to set it up when you want to use the tool, having to deal with changes happening in it over the years, setting up filesystem sharing, etc.

Whereas with Perl it's easy: any UNIX system (and I do mean UNIX in a wide sense, as I've run perl on systems like HP-UX, Solaris, Unicos, IRIX and others) will normally have perl5 installed and you'll be able to just run your software. If it doesn't have perl5, installing it is usually very easy and you don't have to deal with horrors like the python2->python3 transition.