I'm not saying APL doesn't have those features. I'm making examples of languages that have a clear value proposition. If APL is big on immutability and pure functions, then why use APL vs, say, Haskell or Clojure? Same with the "where is the error thing", I was explaining why maintenance isn't just a "depends on who maintains it" thing, in fact the example languages were assembly and Python, nothing to do with APL.
This is literally "people who like it say they like it". It's like saying that the value proposition of Python is having list comprehension, when that's just syntactic sugar.
And no, it's not just me, you just have to take a look at the comments or even the OP. The only point being made is that it has very powerful array programming primitives, but those functions can be easily brought to other languages (and indeed a lot of them have those primitives).
https://www.dyalog.com/uploads/documents/Papers/declarative_...