Specular maps question.

Hi guys. I have a question. About specular maps.

So, materials are meant to simulate real world lighting effects, right?

From what I have read, in nature, specular reflections happens when the incident rays hits a flat and polished surface and generates another ray with the same angle taking as reference the surface normal.



That's the practical results:




I understant the point of normals maps, they change the normals to fake geometry, but the use of specular maps is giving me some doubts:

A rough concrete wall is not flat and polished, so why artists create specular maps for them since specular reflections doesn't happen in such surfaces?
Also, the real specular reflections are like the picture above, I mean, the surface "mirror" the image comprised of the incident rays, in games that reflection is just a "white blur image". This is to reduce the computing calculations?
Also, using normals maps AND specular maps sounds awkward, since a normal map "creates" a rough surface, and in a surface like this there are no specularity.

Thanks, and merry christimas.