It is important to realise that there was no formal canonisation of saints until the canonisation of St Ulrich by Pope John XV in 993. Up to then, and (it seems to me) especially in the 5th and 6th centuries, holy people were proclaimed saints by acclamation of the people. In the case of Ireland, if you think of all those involved in the spreading of Christianity in 5th and 6th century Ireland all of them are referred to as saints - Patrick, Brigid, Columcille, Brendan, Enda, Ciara, Ciaran, Kevin, Mel…the list is endless, but all these saints were known in the communities in which they served as being holy men and women and on their death were proclaimed to be saints by the people. I expect the same sort of thing happened in relation to the early popes, but their naming as saints was probably largely due to the fact that they were the successor of Peter - appointed by God as Bishop of Rome. Certainly from today’s point of view, I wouldn’t read this negatively - as in that our most recent popes are lacking holiness: there are popes even from living memory who are very much on the path to sainthood - Blessed John XXIII, Venerable Pius XII and John Paul II. Indeed, there are many other people - Popes and laypeople - who are certainly saints but because of a tighter canonisation process will not be officially proclaimed as such by the Church.
