If you turn on ADP those photos will be encrypted with a key Apple doesn’t have. They will still be private photos, of course. Even turning on unencrypted backup doesn’t make my private photos not-private.

You say that sharing your photos, unencrypted, with a third party you don't trust, doesn't make them "not-private" and you accused me of twisting language.

Yes there can be private conversations between two people, but there can't be private conversations between two people where one of them isn't trusted but can hear the conversation and simultaneously, what, can't hear it to keep it private?