More precisely: If $v$ is one of the vertices you get when dividing the sphere into 8 equal parts, $v$ will be adjacent to exactly 4 other vertices (its "degree" is 4). Dividing the triangular regions into 4 smaller triangular regions will not change the degrees of these vertices.
When you add the 4 smaller triangles, you are adding 12 new vertices. Each of these vertices is adjacent to two of the original vertices, and 4 new vertices, so they have degree 6.
Not all the vertices have the same degree, so it's not a platonic solid. $~\square$