things are changing ... a little

While it is possible for 1 child's false testimony to ruin a life, these days it would have to be the child's idea to lie.

Police go out of their way to make sure the child's testimony isn't "tainted." For example, they record all interviews involving the child. In some cases, they bring in a trained expert to do a one-time comprehensive interview. The thought is that it will be less traumatic for the child than multiple interviews, AND that since it's done under controlled and recorded conditions, it's less likely to be deemed "leading" and get thrown out of court.

Basically, the police want to cover their asses from true OR false accusations of a McMartin (preschool)-style indoctrination.

Now, if a 12 year old only child of a divorced or widowed father has it in for her father and claims she was made to "suck daddy's dick" there's not much if anything daddy can do or say to refute it, unless maybe there's a paper trail indicating she's lied before.