As in the case of the Heath/Proctor/Bramall/Britton and other cases of False Allegations, "they" are nervous about having to reveal that "Nick" or Danny Day or the dozens of other false accusers lied.

Harder when they have been exposed in a court room (the Victoria station loony; the Simon Warr loonies; the Kato Harris loony; David Bryant; Geoff Long; Ched Evans etc etc etc) but at least they can there cite this terrific law regarding blackmailers being protected by the state with anonymity.

When dead people are involved (like Janner) it's trickier.

And when investigations are set up to examine abuse and find that the crimes have invariably been False Allegations, it is difficult to worm out of telling the truth by admitting it and offending the poor "victims".

The "You will be believed" dogma is still in force.

https://www.thetimes.co.uk/article/child-abuse-inquiry-may-not-examine-ealing-abbey-scandal-9rsdvhc70