FLoC isn't needed to show ads any more than cookies are. If we hadn't gotten everyone used to the gravy of personalized ads, this wouldn't be an issue. But going back to placing ads based on, say, the website or the expected audience in general is like getting the camel out of the tent[0].
[0]: The Camel's Nose - https://en.wikipedia.org/wiki/Camel%27s_nose
I would call it a charity to the site owner whose (presumably) free content you're consuming. What it brings to the user is the ability of the site owner to continue making content.