It is the primary reason that it's prohibited, outweighing any other reason by an order of magnitude.

> I find it hard to believe that a long time technology advocate like yourself is unaware of the fact that the circulation of older CSAM continues to hurt people who were abused in its manufacture.

That depends on how they feel about it. If it is the case that dissemination of existing material reduces the production of new material, no one could be faulted for wanting what they went through to prevent someone else from being forced to go through it too, if at all possible.

> Your comment unfortunately exemplifies the problem of tech people trying to define the problem away rather than directly address the harms involved or propose privacy-respecting technical solutions to proactively mitigate it.

There isn't any known privacy-respecting technical solution and it may not even be possible for one to exist. You can't tell if someone's secret is unlawful without knowing what it is, but anything with access to all of everyone's secrets is inherently a comprehensive violation of everyone's privacy. Any technological solution that could be used for this could not be limited to being used for this.

Fundamentally what you're asking for is the technology to violate everyone's privacy, so that you can violate the privacy of child abusers. But the technology doesn't care what you use it for. It can't be limited to only being used against bad guys.