...allegations, then there will be a lot of perpetrators running around from cases in which the prosecutor doesn't have enough information to go forward.
Trust me - as someone who investigated child sexual abuse - you would be surprised at the number of times something "probably" happened, but the amount of evidence didn't reach the level that would allow a jury to reach a guilty verdict. Preponderance of evidence and even clear and convincing evidence are both easier standards to reach than the beyond a reasonable doubt standard.
It was pretty common for the state to take someone to juvenile court on civil charges and require treatment or protection for a child based on the civil standard even when there were not criminal charges because there wasn't the evidence to support them.