Nut flours

I know someone has asked in the past about nut flours specifically and you said “no” to nut flours also under the no flour rule. Why specifically no to nut flour? I’d like to understand more about it as my brain always wants to know the why behind things when people tell me not to do something. Does having almonds or cashews or what have you in a ground flour form change the glycemic index of it somehow?
Thanks lady!