It's not explicit in the directive, but it is right there in the working docs so it's pretty clearly a principle:
> the Working Party considers that first party analytics cookies are not likely to create a privacy risk when they are strictly limited to first party aggregated statistical purposes and when they are used by websites that already provide clear information about these cookies in their privacy policy as well as adequate privacy safeguards.
You left out the context of your quote[0], where the Working Party explicitly states that first party analytics are not exempt from Article 5.3. Your quote leads up to their opinion that they _wish_ it was exempt, since it represents little privacy risk, but that it would require the article to be re-visited.
> the Working Party considers that first party analytics cookies are not likely to create a privacy risk when they are strictly limited to first party aggregated statistical purposes and when they are used by websites that already provide clear information about these cookies in their privacy policy as well as adequate privacy safeguards.