I’ve never enabled iCloud backups and it has never pestered me about it after the initial iPhone setup process (the modern version of which doesn't even pester me then since it copies the setting from my last iPhone). I backup locally to my mac, which admittedly they made require a password each time now, which is a bit annoying, but it’s not asking me to enable icloud backups regardless.
No, but I haven't seen Windows ask multiple times a day either. But iOS does try to get me to turn on iCloud every time the phone reboots and somewhat randomly without rebooting.
(I've had it turned on for so long that I honestly don't know what they do.)