It's not reviewers. It's devs using built in background streaming to do optimization patches (smoother fps, more pixels...on both consoles), which is fine but devs should take care to be sure reviewers have all patches prior to doing a review. That should be on devs to get them that content.
Publishers are usually pretty solid when it comes to information regarding game-improving patches. It makes the whole framerate situation a bit dubious. Only Digital Foundry can save us!