Before Perl, there was no scripting language that could do systems tasks except maybe shell and tcl, but that's shell is an extremely unpleasant programming experience and the performance is horrid, and tcl's string-based nature is just too weird.
Perl gives you something more like a real programming language and can do shell-like tasks and systems tasks very nicely. Compared to what came before, it is amazing.
But then Ruby and Python came along and checked the "real programming language" box even more firmly than Perl while retaining the shell/systems angle. Ruby and Python were better than Perl along exactly the same axis as the one on which Perl was better than Tcl and shell.
I like Perl and used it professionally for year and vaguely remember probably around 2010x relatively massive Python evangelism (lots of articles, conferences, lots of messages from Python adepts on forums e.t.c). One of talking points (no longer needed nowadays) was that Python is backed (sponsored) by Google so Python will be successful and you should not worry about it's future and also if you will choose Python you will be successful (as Google is).
For me, this is why python took off. People wanted that lucrative job or receive the reflected glory of a winner, so y'gotta learn python. The rest is just post-hoc justification for why you made that choice passed on as "this language is better because of blah..."
A lot of the justifications don't stack up against serious scrutiny, but are accepted as gospel.