I left it out intentionally as while I personally think it's in the same category, it's unfortunately sufficiently normalized as to pass without question.
There are medical reasons for the removal of foreskins such as phimosis [1]. Inasmuch as I would agree that religious justifications for circumcision are the ramblings of a cargo cult, circumcision itself was and is (for now at least) not without value.
There also could be medical reasons for the removal of arms. That doesn't mean parents should be allowed to remove the arms of their children as they are born.
If there's a medical reason to amputate an arm and if it would be appropriate to attend to it immediately after birth so that no long-term complications arise from a delay in action, a parent should acquiesce to it. If parents shouldn't make that decision then who should?
I left it out intentionally as while I personally think it's in the same category, it's unfortunately sufficiently normalized as to pass without question.