an obscure but very powerful matrix-centered programming language usually considered to be "write only", as in impossible to read what someone else wrote.
Find the "write only" comments you commonly see online to be untrue. I have been writing a voxel game in majority APL code for the past 6 months. I have been able to read my own code and refactor stuff I've written months ago fine while also integrating code from other APL codebases and suggestions from other people. It just has a higher learning curve to understand.
Yes, perl is considered write-only because it is a mess of features that allow unhygienic programming habits to flourish - it is full of hard-to-trace magical behavior. Completely different than APL, which has had perl's write-only label applied to it by programmers not used to reading terse mathematical notation.
40 years ago (at school) I generally wrote in ink - edged and straight nibs, blue and black ink because I liked it. I learned several formal styles as well as my idiosyncratic efforts. I did have biros and fibre tips etc available. I had loads of choice. My parent's generation was probably the last of the ink and nib first users.
And checking the article... Tags: apl
Can you even read what you wrote several years ago?
Its origin is as a mathematical notation for algorithms. It was used to publish research reports and (IIRC) a book or two.
You're confusing "possible to read" with "accessible to people unwilling to invest any effort understanding"
Only by the ignorant and uninitiated.