Really? I did a quick grep in ghostty (160k lines of Zig) and found four total references to @fieldParentPtr. I'm still a Zig baby, but I have not seen very many references to @fieldParentPtr at all.
I would expect the inheritance pattern to be quite rare in performance-aware software design overall, since such constructs tend to be rather cache-unfriendly. So I would attribute the low number of references to inheritance being rare, rather than @fieldParentPtr not being used for inheritance.
