

You can still very easily use macOS without an Apple ID or iCloud account, actually. You lose out on iMessage, FaceTime and the App Store, basically. But that’s about it. And they don’t nag you about it ever again unless you try to send an iMessage or what have you.
On iOS and Android it’s effectively a requirement though, because App Store / Google Play. Phone is not too useful if you can’t install any apps.
True, but realistically for most people the lack of Google Play is a non starter. Unless you’re really technical and committed to FOSS, you’re going to need every day apps in there.
IMO the biggest issue on mobile is not even the stores but the fact that both platforms are so tightly integrated with the cloud and the account signed into the OS. Again, if you’re an ordinary user, you can barely do anything without it being tied to your Google account or whatever. Everything from maps to notes to music, it’s all tied up in that.