> [...]
> Cultural conservatism as a first principle.
Counterpoint to this: Rust. Rust has a similar RTFM/"wizards" culture, but is not culturally conservative (in any sense of the word).
My two cents: Perl's "culture" had little to do with its fall. I think Perl's problems run much deeper. Perl is built on rotten foundations. It's fundamentally a scripting language (albeit with bolted on additions to make it kinda-OOP), and it therefore has all the problems that scripting languages have for building large software projects.
Those problems have no quick fix, and indeed fixing them would require throwing the language out entirely -- at which point, why not simply switch to another language entirely (which is exactly what happened...).