> No modern systems have such trap representations for pointer types
This may be incidentally true, but "address sanitizer"-like features are becoming more common on modern hardware, and while these do not currently trap on creation/manipulation of a 'wild' pointer (since, strictly speaking, a trap only happens on dereferencing), there's no solid reason to expect this to remain the case in the future.
I don't see how you could trap creation or manipulation, since those pointers are stored in registers and/or memory, and both are fundamentally untyped. How would the hardware even know that something is a pointer, on any architecture that is popular today?
Because you use typed instructions to access them. For example, on ARM with pointer authentication you’ll sign pointers and unsign them right before using them. If you forge a pointer it’ll cause a crash when it’s used because its signature will be incorrect.
This may be incidentally true, but "address sanitizer"-like features are becoming more common on modern hardware, and while these do not currently trap on creation/manipulation of a 'wild' pointer (since, strictly speaking, a trap only happens on dereferencing), there's no solid reason to expect this to remain the case in the future.