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Correct, if you want to live cookieless on the internet you have to disable them in browser. But as others have said, this will break the majority of websites.
Functional cookies can never be used for identifiable information, only to ensure the functionality of the website.
There’s many reasons, site specific settings like selecting a language or if a certain popup message been dismissed by the user so it’s not shown again. Sorting settings, dark/light mode or what stage of the signup process the user is at.
Altough I agree many aren’t a necessity and could be eliminated by better software design.