It's clear that huge swathes of physics are deterministic! Or at least anything non-deterministic is on a small-enough order that we can still build rockets and keep clocks on satellites and earth in sync.

And I agree that a world completely free of causality would be a useless world. But I think that a world that is completely closed under physics and completely deterministic isn't compatible with a "free will" that could support a system of ethics, which I think is where a lot of people then want to take the "does free will exist" argument once they figure out the first part. So it's a matter of threading the needle.