Since the kids who leave never became part of the community as adult, they didn't break any religious law when they left, so they are not shunned.

There is always a danger that meidung may give birth to a canton of outcasts which expands to become the Alpha dogma.

If this happens, no-one can tell the difference between meidung and yurdung and all hell breaks loose. [In fact, sometimes a canton of outcasts can become an entire country ... like Australia, a classic case of Oztracism.]