I also need to ask: why are the primitives built INTO the compiler? Is
there any sound explanation for this?

One reason I could think of is to force the linker to keep those
symbols in the final output file (when using -output-obj). But if
they're not used, then why do they need to be present? For Dynlink to
work correctly?

This seems to be the -one- thing to make building my custom compiler
environment not work without requiring a customised ocamlc (with less
primitives builtin).

Jonathan