This policy means there is a "dark web" on Rumble, where videos exist but no one finds them. If the videos do not appear in a Rumble search, they will receive less views. Only those that are given a link in some other form will even know the video exists.
This policy also acts as a form of soft censorship or shadow banning. If Rumble does not approve the video for monetization, for whatever reason, then the video will not appear in a search result.