I feel like I grokked Perl enough and I still write Perl code, but I also think that there are some technical reasons why it declined in popularity in the 2000s and 2010s. All those differences between $ % @, the idea of scalar or list context, overuse of globals, and references. These features can all make sense if you spend enough time in Perl, and can even be defended, but it creates a never-ending stream of code that looks right but is wrong, and it all seems to create a lot of complexity with very little benefit.