Also, the whole point of disabling iMessage (in this thread) is to close the iMessage-related zero click exploits described in TFA.
And are you really sure that Signal or your preferred messengers don't also have Zero-Click exploits? After all, they aren't sandboxed to the degree iMessage is with BlastDoor.
Signal does not escrow endpoint keys in an iCloud Backup, so your first statement is incorrect.
Also, Signal putting your escrow keys in iCloud? I don't think you know what you are talking about. You can set iMessage to not put your keys in iCloud like I said above by turning off iCloud Backup which makes it fully End-to-End with your own key on your device, just like Signal.
If you are worried about the other party having their conversations being backed up, tell them to disable iCloud Backup. If you are this worried about the privacy of your communications, hopefully the other party would be as well.
And Signal and any other E2E messenger is absolutely storing copies of your key on the recipient's phone, just like iMessage would. If it didn't, there'd be no way to verify that a message was sent from the same sender.
You will be forced to make compromises somewhere unless you want to live under a rock in the desert. You can't drive without a State ID, can't get a home loan without credit, can't work without a Social Security Number except under limited circumstances, can't make money without reporting to the IRS, and so on. It's entirely about what compromises you want to make, and the tradeoffs therein.
Something like 96% of human beings don't have a social security number. Many of them work.
The technicals are different, the point is the same.
