"“We offer call history syncing as a convenience to our customers so that they can return calls from any of their devices,” an Apple spokesperson said in an email.”Device data is encrypted with a user’s passcode, and access to iCloud data including backups requires the user’s Apple ID and password. Apple recommends all customers select strong passwords and use two-factor authentication.”
Not defending Apple here and I only have an iPhone (no other part of the Apple ecosystem) so I can't speak to the need (or usefulness) of being able to return a call from my iPad or Mac if I miss a call from my iPhone. This just smacks of more Siri/cloud/Cortana data collection garbage to me.
Heck, I'd have the iCloud completely turned off still if it weren't for their "new" feature where they stopped syncing with Outlook notes and I had to have someway of backing up/sync'ing note items with the rest of my PCs. (I backup my iPhone to an abacus at home...)