Unstructured self-commitment lacks the social force of institutional vows. [causal]
The demands made by this commitment might sound commonplace—after all, monks of various religions have chosen celibacy. They do so, however, with substantial social and institutional constraints to keep them celibate, and even then they often fail. Alberich commits himself without any social structure to give him the incentive to stay unloving.
Russell Hardin, Trust and Trustworthiness, loc. 195