I see your point. If you're the kind of user who keeps automatic image download disabled, and rarely downloads them manually, keeping Mail Privacy Protection disabled might actually be more private. Fortunately, it isn't automatic. You'll have to enable it.

But if you do download a tracking pixel, email marketers already know you are using an Apple device. I see the Mail Privacy Protection feature as being primarily for people who want to automatically download images while sending less PII.

Only if you have a foolproof way of knowing Apple IP adresses