It just goes to show how readily people protect institutions against "scandal" - the reputation of the institution is more important than the damage done to individuals. We have seen this time and again with the RC Church - which even now is still struggling against the the need for openness.
That political parties should be seen in a similar way by their adherents is not really surprising - they are, after all, highly assailable belief systems. (Just look at Theresa May's continuing attempts to put the interests of the Conservative Party before those of the United Kingdom.)
Organisations believed they were protecting their good name. I knew a teacher who was a housemaster in an independent school who systematically abused pubertal boys under his protection. He was told to go somewhere else and was given a good reference. About thirty years later he was convicted and jailed.