Perl 5 was abandoned largely because extending it became so painful, and Perl 6 was this crazy waterfall design process for the first few years. Perl had mostly lost all momentum, by the time Perl 6 development started to get traction.
My experience was that discourse around Python also tended to be more civil and humane, and that came from the top (Guido & Tim.) I think that played a role in or was otherwise somehow connected to the better engineering discipline.
It's all relative. Perl 5 is more active now than at any time in its history.
Python has expanded 20x in the last 20 years. So Python has in relative terms eaten Perl's proverbial lunch and overshadows Perl so much that it's easy to think Perl just died. But it's actually successfully scavenging and growing nicely in the shadows despite the 20 year long drumbeat of pronouncements of its death.
From my perspective it does look like extending Perl 5's core is painful but that hasn't stopped it growing to a half million lines of change a year (and many millions a year in the upper reaches of the CPAN river and tens of millions further downstream) and folk writing ever more powerful pan ecosystem tools as, eg, described in this report from a couple days ago:
(That all said, I'm personally more focused on Perl 6 which is a new ball game even while it's also an extension of the old one in the sense that it cohabits in the same ecosystem and culture.)
Over the last couple of weeks I've been training people who've been stuck in svn for far too long to use git. My go to three sentences to help orient them has been "git is like perl. It's extremely useful and there's nothing you can't do with it. The problem is there's lots of different ways of achieving the same thing."
I'm not sure your argument that 'top down decisions are good' is why is valid. And the whole 'whitespace is syntactically meaningful' thing in python gives me the heebeejeebies. On the other hand when I decide I need to learn more maths, python and sympy is the tool I reach for.