> The "why they require a CLA" is for enforcement.
None of that seems like a "why" to me; to cynically paraphrase it, "our policies require our polices." Why does your record-keeping require a CLA? Why is a CLA required to enforce the GPL?
A CLA is required to be able to sue someone infringing the GPL and represent yourself as the legal owner of the entirety of that code. If you have a hugely fractured ownership like Linux, it may be very expensive to bring a suit against an infringer.
None of that seems like a "why" to me; to cynically paraphrase it, "our policies require our polices." Why does your record-keeping require a CLA? Why is a CLA required to enforce the GPL?