I think people mistake what they are most useful for. Pulling someone’s plates off the video is hard if there’s any distance between you. What it’s good for is establishing what actually happened. Someone driving down the freeway sideswipe you? They might argue you moved into them. A dashcam proves who did what. Well, to be more precise, it proves what happened from what you can see from your windshield (and maybe rear window if you have a rear cam). But it can establish you were in your lane.