The only logical explanation I can see is that these are two decisions:

- linked lists aren’t useful on modern systems because traversing them causes to many cache misses. Therefore, we shouldn’t provide such a simple implementation.

- but we need one in low level OS code, and there, intrusive lists are preferred. Their limitation that you cannot store an object in multiple lists isn’t a problem, and the extra speed and the fact that you can move items between lists without allocations is desired.

I don’t see why the intrusive implementation has to be so basic, though. Can’t you, in Zig, express that a generic type T used in a generic list class has to have a nullable next field that points to a T?