You comment reminded me of the USBCSA, better known as the Shakers, a religious community which began in the 18th century, spreading via proselytism, espousing ideas and artistic tendencies 2 centuries "ahead of their time", but ultimately dwindling down to 2 members as of 5 years ago. As proselytism slowed, one of their particular tenets, celibacy, ensured whatever virtuous facets (subjectively measured, of course) of the community would cease to be reproduced.

Moral, perhaps, but not self-sustaining.