[angoragoats]

This is false; there are ads in quite a few places in macOS, examples of which were shared in another reply to your comment.

While I'm not a Windows user much anymore, my understanding is that there are at least unofficial hacks/tweaks you can apply to remove many of the ads in Windows. In contrast, certain ads in macOS (e.g. the one nagging you to upgrade your iCloud plan when you're near your storage limit) cannot be disabled through any mechanism that I've been able to find.