[Rygian]

Marketing cookies can be same-site or third-party.

The only entity that can specify whether a cookie is marketing-related or not is the website. No one else can.

[zasdffaa]

You're right of course but 3rd party seem to be the great majority, so blocking them is a big easy win. Also, only 3rd party cookies can track between domains/sites, so that stops that, or so I believe.