Exactly like GDPR shouldn't have mandated millions of websites to pop up a consent form, as a global browser setting could would have set consent as a user preference.
But the objective of these regulations aren't what it says on the tin.
The GDPR doesn't directly mandate cookie banners though. It wants consent from users prior to processing their data.
Also, the browser flag that indicates no consent already exists: https://globalprivacycontrol.org/faq
The objective is exactly what it says on the tin. The malicious compliance is someone else's objective.