OEM paint loss in rain rails- is this normal?

That is the factory caulking, and the paint does come of of it before anywhere else it seems.
Mine is coming away from the metal at the edges so I have to do something with it.
I asked on here if removing the caulking and using POR15 in the seams and then painting it would be reasonable and most everyone told me that it won't work because it's a seam and it would crack the POR and the paint then it would leak.
Well, I tried it anyway about 6 monthes ago in a spot about a foot long close to the top and it has not cracked at all. (not the POR or the white enamel either one) so I may continue it on the rest of the rail.