Have you looked at twitter or Facebook and seen the swaths of our population that are just fully believing fake AI slop about politics, crime, etc?

Most of those people wont be checking the provenance of the images. FB have stopped from their fact-checking processes.

Only the investigative or journalistically inclined will make use of this, and those people already fact check.

Where’s the en mass gain?

There's a world where all the big platforms automatically flag AI images thanks to SnythID and other techniques. The more ubiquitous it is the easier it will be for them to make that a reality.