I think the context is missed here. It's a useful tool, but should it be an active-by-default feature shipped with the browser? It doesn't add security and doesn't enhance speed. Wasn't it more acceptable if this was an add-on?
The integrated Pocket does show some "suggestions" on the default new tab page. But I don't see any ads on them, and sometimes they are pocketed articles from paid-subscription resources like e.g. The Atlantic. It it's a kind of paid content advertising ("we pay you to bring more readers to this ad-free text page"), it can't be a very lucrative service.
Disclaimer: I actively use Pocket, but I'm not a paying subscriber of it.