I (a layman) believe that part of the "global" scope of the law is to enable actions at home (and some pressure).

If they want to order ISPs to block services there needs to be some legal framework to do so. "We contacted them, they didn't respond, now we need to revert to blocking" sounds pretty convincing to me.

For your other argument I'll ask the question I ask anytime this comes up: How would you propose laws/regulations on online services are enforced if not (at least in principle) globally?