A cool thing is, you can achieve the same effect by rotating the table in a circle (if possible) until you find a stable angle, since for 4 points on a circle there has to exist at least one rotation angle where they are on the same elevation.
I don't think that's exactly right. to create a plane you only need 3 points and 4th point can be on a different height than that plane. A different thing is when the ground itself is uneven and you manage to make both fit to the same shape.
There's no guarantee you can draw a circle through the bottom of the four legs of a table (opposite legs can be off in the same direction). Also, most floors are not perfectly flat, therefore you can't assume the floor is at one elevation.
This requires the legs to be all the same height and the floor to cause the wobble. That doesn’t happen often irl, but I’ve done it a few times and it always makes me happy when it works