Maru knows that well, but this is tutorial for glossiness :- ). Of course, he also used the fresnel map, but he doesn't write so in his tutorial so you would have to read between lines otherwise it's confusing.
Well, it looks good but it's incorrect, or semi-correct, to certain degree. The GGX handles the falloff well, but rough materials do have glossy 'retro-grazing reflection' where they appear mirrory close to grazing angle, but not
to such degree as in your example. Your curve is too benevolent and it looks like blend of two materials too obviously, far too soon before grazing angle occurs.