Yeah, great point here. Facebook really emphasized this difference awhile back when they started allowing users to "Like" a Page, but then choose to hide it from their News Feed.
This allows me, as a Facebook user, to complete my profile and declare that I like something, even if the marketing that the associated Page is doing isn't something I want to see.
This ensures that profile information remains accurate, which is critical for ad targeting - people don't start unliking things they actually like, just to avoid annoying marketing. The interest graph remains intact even when brands make poor marketing decisions.