Perl's decline was cultural

Spot on: the toxic culture around the language was a nail in its coffin.

A classmate who introduced me to Linux in the early 2000’s was a Perl enthusiast who completely embodied the RTFM mindset. If someone didn’t already know something they were mocked. We ceased to be friends after a number of these interactions.

The cult of RTFM is so painful to interact with and off putting. The concept is sound, reading documentation is important. However simply responding to all questions with "RTFM" is not only not helpful but as often as not useless advice.

The documentation for something may not exist, may not be clear, or may just be wrong. Unless you specifically know the answer to a question is laid out clearly in the documentation, blindly telling someone to read the documentation is just being a dismissive asshole.

A much more productive and helpful response is "did you RTFM?" or "check section X of the manual". But those sorts of questions require the desire to not be a dismissive asshole.

The cult of RTFM has always been an impediment to Linux becoming more popular. When I was first learning Linux...almost thirty years ago now...the cult of RTFM nearly put me off the whole endeavor. I was asking for help with "Xwindows" on IRC and the responses were either RTFM (which I had done) or pedant diatribes about "it's X, not Xwindows newbie! It's not micro$oft!" Which was a super fun to deal with. The experience steeled my resolve to at least ask someone if they read the manual before assholishly telling them to do so.