It shows no such thing. It shows that you have found something you think you can be productive in and that you like, not that the rest of us are on the wrong track.
I can't agree. (BTW, I don't like K, and I don't use it, but if I did I'd like to think I'd be productive in it.)
This little system runs circles around entire sub-industries of other software. The fact that it exists and uses one or two orders of magnitude less time and code than other systems is significant.
It's like axes vs. chainsaws. If the job is to log a forest the latter will be better than the former.
Less code is entirely irrelevant unless for some reason you're concerned about a few k of storage for your source, less time appears to be speculation.
If people can make working, maintainable software other ways, particularly if those other ways have large, established ecosystems of dependencies, then they are likely doing it right regardless of how much you like apl.
