That's a tedious debate that has been rehashed to death. Finding somebody who has CSAM without being a child abuser doesn't save even a single child. Finding everybody who has CSAM without being a child abuser would likely save some children (drying out commercial operations, perhaps?), but is also basically impossible.

And how many children can really be helped in this way? Surely the majority of child abuse happens independently of the online sharing of CSAM.

And is that really worth the suspension of important civil rights? That is really what this discussion is about. Nobody is arguing against fighting child abuse, the question is about how, and about what means can be justified.