This is not actually the case. APFS can continue to behave as a case-INsensitive partition (check the options when creating a new APFS volume), and remains so f

This is not actually the case. APFS can continue to behave as a case-INsensitive partition (check the options when creating a new APFS volume), and remains so for the system partition, I guess specifically to avoid any hard-to-debug compatibility issues.