I don’t know if that’s the case, simply because all code that I see written by array language programmers looks like code golf. Even the language implementation itself!
Is this because all the code you see is through HN or similar? No one's going to share something titled "an unremarkable script I use to help run my business" here. Not sure what your threshold for code golf is, but you can see APL written in a variety of styles by searching Github. It doesn't recognize K but does have Q, which is basically K plus keywords, obviously promoting more verbose code. Whitney originated the dense style of implementation shown at your link, and a few other implementers (including myself in the past) have picked it up, but it's not that common. For example April, GNU APL, Kap, Goal, and Uiua all use an idiomatic style for their implementation languages.
https://code.jsoftware.com/wiki/Essays/Incunabulum