I don't know Olin Shivers but I've read enough of his writing to know that this acknowledgements section was written with tongue in cheek, and in fact it's a funny enough piece of writing that I've shared it a number of times like the grandparent comment did.
I guess the author was thinking of how cat's original purpose is to concatenate multiple files, not show just one file. (But I certainly don't think using cat in the latter way is a misuse.)
There's also a commonly noted "unnecessary use of cat" where people do this:
cat file.txt | grep foo
instead of this:
<file.txt grep.foo
but that's not relevant to bat (which can be used unnecessarily in the same way).
(1) lack of primitive hash tables (2) lack of primitive arrays
I'll note that if there are primitive arrays and the compiler optimizes arithmetic, the rest of the hash table can be implemented in Bel.
Also, maybe a Sufficiently Smart Compiler could prove that a list's cdrs will never change, store it in cdr-coded form, and treat it like an array (with the ability to zoom right to, say, element 74087 without chasing a bunch of pointers).
The “stair-steps” you see in your DAW when you zoom up on a digital waveform only exist inside the computer. [...] When digital audio is played back in the Real World, the reconstruction filter doesn’t reproduce those stair-steps – and the audio becomes truly analogue again.