Maybe when God told all believers that they were a royal priesthood, thereby doing away with the need for intercessors or other intermediaries.
1 Peter 2
Wherefore laying aside all malice, and all guile, and hypocrisies, and envies, and all evil speakings,
2As newborn babes, desire the sincere milk of the word, that ye may grow thereby:
3If so be ye have tasted that the Lord is gracious.
4To whom coming, as unto a living stone, disallowed indeed of men, but chosen of God, and precious,
5Ye also, as lively stones, are built up a spiritual house, an holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ.
6Wherefore also it is contained in the scripture, Behold, I lay in Sion a chief corner stone, elect, precious: and he that believeth on him shall not be confounded.
7Unto you therefore which believe he is precious: but unto them which be disobedient, the stone which the builders disallowed, the same is made the head of the corner,
8And a stone of stumbling, and a rock of offence, even to them which stumble at the word, being disobedient: whereunto also they were appointed.
9But ye are a chosen generation, a royal priesthood, an holy nation, a peculiar people; that ye should shew forth the praises of him who hath called you out of darkness into his marvellous light;
10Which in time past were not a people, but are now the people of God: which had not obtained mercy, but now have obtained mercy.
Somehow the RCC managed to ignore this part of the instructions.