That's not true, you need to provide a password to read the passwords saved in the browser whereas cookies can be read without any hassle from the developer tools

Cookies can also be queried programmatically, whereas passwords need to have the users auto fill active and interact with the input element

Most extensions have effectively full access to your cookies, not to your passwords - which is a real attack vector (session exfiltration) which is actively being used by had acteues

There are ofc server set cookies which are not programmatically queryable, but that's not the norm (and they're still visible via the developer tools, so the core statement remains untrue)