It is very, very rare to see a buffer overflow in D because the use of these arrays is so easy, convenient, and robust.

Not only does it virtually eliminate buffer overflows (when used), it is more efficient than 0 terminated strings. It does not need to scan the strings, nor does it need to load the string into memory to determine its length.

I understand your concerns about mixing it up with 0 terminated strings. They are real, but have not been a particular problem in practice. What happens is one simply moves away from using 0 terminated strings. A zero terminated string can be converted to a length one with:

    a = s[0 .. strlen(s)];

There are string libraries that work that way in C.

If you do it manually, without a lib, then you need to check that the length is valid yourself (after every operation), so it's not as useful as a language with first class support for it.

It boils down to being inconvenient, unreliable, error prone, and difficult to audit. That's why it isn't used and C's #1 problem remains buffer overflows. And so it goes for all the other solutions for C for this problem, except my proposal.

My proposal is how D works, and it's been convenient, reliable, robust and auditable for 20 years. You can still use raw pointers in D, they are fully supported, but the use of the arrays make use of raw pointers rare.

Or maybe they omitted it before there are literally hundreds of languages that were inspired from C and listing them all would have been boring for the reader.