With first learning to stand, as I imagine anyway (can you remember learning to stand up?), when you first give it a go, it seems like there is very little room for error. Lean too far in any direction and you're going down before you know it. But once you get the hang of it, there is a lot of leeway between standing/walking straight up and actually falling over. Most of the time, we are actually in this previously unavailable middle ground without even thinking about it.
In much the same way, learning to balance the amount of flash with the available ambient light in a photo is tricky. At first I always over-lit the scene with flash. Of course - I was learning flash, so the more the better, right? Um, no. Dial it back and now it doesn't look any better than without flash. Why is this so hard? I just kept falling down.
With more experience, I'm (very, very slowly) learning that there is a lot of interesting to be had between that over-lit nuked look and the not-there under-lit other extreme. There doesn't even seem to be a "right" answer - just a whole bunch of different "feels" to be discovered.
This one just needed a tiny hint of (ceiling-bounced) flash, to bring out the details in the otherwise dark room.
Inquisitive little minds will figure this balancing thing out - some of us (him) sooner than others (me).