In the early days of Buddhism, the sangha was of high, pure quality. Thus it was enough to use the "teaching pratimok.sa" as moral encouragement during the half-monthly communal congregation, there was no need to enforce strict regulations. With the further development of Buddhism and increasing offerings made by lay sponsors, however, worldly minded people inevitably crept into sangha ranks and lived there in defiance of the dharma. Only then did the Buddha additionally establish the vinaya employing the "authority pratimok.sa" as a corrective means. Those transgressing it were punished in order to deter others from unlawful behaviour.
"Vinaya" has the double connotation of "training" and "taming." Originally it referred to all methods to tame mental afflictions (the higher trainings in ethics, concentration, and wisdom) that are contained in the discourse and rule collections, yet in the course of the development of the sangha as an institution its meaning narrowed down to the sangha's higher training in ethics, i.e. the pratimok.sa and the skandhaka.
There were three reasons for establishing rules:(1) to remove obstacles from the practice path of individuals; (2) to create an optimal environment for the practice and spread of the teaching in which the sangha might happily and purely live; and (3) to avoid criticism and let the laity engender respect towards the triple jewel.
Of course, it was impossible for the sangha to develop into a dictatorial direction because this would have been in contradiction to the basic principle of dependent origination. Thus there has never been a national or global "vatican" or a highest pope-like authority in the history of Buddhism. If we want to curb the disorderly phenomena presently rampant in the Buddhist community it would be dangerous to take the path of a powerful central authority. On the contrary, it is necessary to change the sangha system of "teacher's authority" which was influenced by the patriarchal nature of Chinese society, and return to direct democratic processes stipulated in the Vinaya by reintroducing direct democracy within certain boundaries while giving the responsibility for certain coordinating policies temples and monasteries themselves are not in a position to carry out to the indirect democracy of a central authority -- under the condition of a sound system in the temples and monasteries on the grass-root level.