I think what you're hearing is that your preference for these sacrifices in furtherance of the end is not shared by some other people.
As for specific faults, that's not really necessary, plenty of general ones have been shared (like the lack of transparency, potential for abuse) which do not need specifics to be understood.
As for evaluating one vs. the other, I feel that your opinion as to the result of that evaluation might not necessarily be mine, and neither of us will convince each other, as a result of the fundamental difference in the amount of privacy each of us is willing to give up, and in exchange for what.
However, as others have also pointed out, child sex abuse has both existed and been prosecuted before this law has come into effect.
Thus, the alternative I personally prefer is that. I understand your principles and willingness to sacrifice privacy lead you to another solution, but hey, you asked.