It'd be a wide pyramid, sure. But nothing says they need to be skinny.

#pyramidAtAnySize

You're right, but it's not really about the angle. Talking geometry, the pyramids of Egypt are 'square pyramids'. Four triangles on top of a square base, meeting at a point, or vertice. A cube, however, is six squares at right angles to each other, three faces meeting in vertices. The point at the top of a pyramid will look a lot different than a corner of a cube, because it's a completely different number of planes meeting.