Apple themselves addressed "why", summarized here:

https://news.ycombinator.com/item?id=28176418

The facts remain that: a) Apple's new system is strictly superior to PhotoDNA in every respect people complain about, including malicious insertions of non-CSAM hashes (since you'd need 30 matches with Apple, and 1 with every other online service); and b) concerns about the local implementation mostly rely on fear of the unknown and illogical arguments (Apple's system makes it no more likely than before that we'll see backdoors in their OSes, and if that ever happens researchers would certainly discover it).

Or, more obviously, the internal memos from Epic trial saying Apple has a CP problem coupled with a desire to create a system they could run on encrypted photos (assuming this is a missing piece for full E2E).

That's exactly it! The entire C-suite is left defending Apple's brand in an antitrust trial on the basis of propriety ,[1] that Apple has the adults in the room, which has been the impetus for the abrupt hard turn away from privacy. That narrative leaves me feeling very little sympathy for Apple, unfortunately.

[1] https://mlexmarketinsight.com/news-hub/editors-picks/area-of...