Reform Judaism is hardly the exception. It's by far the largest of the three major branches of Judaism in the US, larger than the two major others combined. (https://www.pewresearch.org/fact-tank/2021/06/22/denominational-switching-among-u-s-jews-reform-judaism-has-gained-conservative-judaism-has-lost/,current denomination question has reform at 33%, conservative (which has woman leaders) at 18%, and orthodoxy (which a woman leaders but is still fighting itself about it) at 8%.)

That's not an exception at all.