Why does OpenBSD need this?

OpenBSD does not need this.  The mechanims you are finding exist because
we (OpenBSD) need them in the base, already, for various reasons.

But you have not explained why we need more.

If this is just for you -- answer is going to be no.

You want to build a static only OpenBSD?  And then what?  You'll run
that?  And sometime in the future you'll hit some bugs, which may or may
not be caused by your local OpenBSD-but-actually-not-OpenBSD-at-all, and
you'll submit vague bug reports and send people on wild goose chases?
I've been around the block more than a few times, and the result is that
I despise unused flexibility.