flocke
An issue in writing a thoroughly helpful response, is that successful APL and K implementations are usually applied in a largely corporate and proprietary context.
I lack a list of applications to link which you could look at.
However I'd still say APL/J/K applications require vastly less resource, and initial investment than most tools whilst providing on-par or greater computational power.
In fact, APL/J/K are simpler to read than most languages![1] Programs consist of functions and higher-order functions that are applied to array(s) in an infix or prefix style. These are evaluated Right-To-Left with minimal precedence rules.
Given a few days, the core language(s) can be easily memorized[2][3][4].
The issue, at it's roots is mostly confidence. And that's a cultural issue APLers are constantly alleviating. A part of that is countering the spread of dishonest framing and narratives.
[1]: https://xpqz.github.io/learnapl/intro.html#but-it-s-unreadab...
[2]: https://awagga.github.io/dyalog/voc/