I am not the author but in this case the form of the language supports the differentiated function that might make it useful to someone versus some other class

I am not the author but in this case the form of the language supports the differentiated function that might make it useful to someone versus some other class of language. Sophisticated concatenative language designs can naturally express certain things that are pretty difficult and awkward to express in more conventional programming language idioms. An example, and the implementation problem that introduced me to concatenative languages, is software that does automated program induction. The downside is that these languages are difficult to optimize for conventional silicon -- you would not want to use them to build software they are not uniquely good at. While you could build layers that express a more conventional set of language idioms, most of the value in using this language as opposed to some other will be in exploiting the unconventional expressiveness of the mechanics.