If the postulant doesn't have the parent's permission the sangha can and will accept a dukkata. I know of one such case in Burma, I'm sure there are more elsewhere. The question about the eczema has more to do with taking advantage of the healthcare that Sangha members might get from doctors who would offer their services free to Bhikkhus. At one time there was an outbreak of some skin condition and it seems that people were taking ordination because they knew they'd get free care from a doctor who'd offered it to the sangha. So, it isn't specifically about eczema or ringworm or anything like that.