One has to understand the unique position of the Catholic Church in history versus the other Christian denomnations.Wasn't purgatory created by the Pope as a way to get people to spend money and buy indulgences?
After the fall of Rome, and the invading hordes, it was the only organization of western civilization left and it necessarily filled the political vacuum for centuries. Like any other politcal power, laws and rules were made to keep order...and like any other political power, was subject to corruption.
The Church is the only Christian entity that can trace its roots directly back to being founded by Jesus Christ....all other Christian denominations sprang from reformation of the Church. The Church itself continues to self evaluate, sifting thru centuries of rituals determining that which is critical and was 'from God' and that which was man made. Hence the 'waffling' on concepts like purgatory, limbo, etc.