It just injects additional randomness into randomness that is already perfectly fine. It's basically for PR/show, but it is actually used. But without it, things work fine too.
This is why, in an app, you might seed with timestamp and process ID and /dev/urandom, in case any of them happen to be non-unique or unsupported.
Prevents not only technical issues but attacks like someone blocking the camera or putting a static photo in front of the camera.
Now I wonder about some periodic offsets. E.g. if the lights are off at night, or if the skies are overcast in winter, does it skew the results in some significant way. I seriously doubt that though.