Not really. You can do it with 2 commands if you know the two angles or one command if you know the angle and the cross product. Its equivalent. It just depends what information you have.
If you just have 2 vectors in 3D space, and you want to use 2 commands, you have to project the angles onto YZ plane for rotateX and the XZ plane to rotateY. This can be done by trig, but its just easier to use the dot product.
On the other hand, if you don't have 2 vectors, but just 2 angles you want to turn, then use the two commands, makes sense?
