Capillary action occurs when molecules in a liquid have a greater attraction to the surface of a solid than to each other as they travel along that surface. Therefore, when water passes over the edge of the roof, it will remain attracted to the surface of the dripping edge and will run behind the gutter. You may see water dripping behind the gutter or even running down the wall during the rain. If it lasts long enough, water stains will start to form on the wall.
If you notice this happening to your house, but the gutters appear to be glued to the wall, the problem may be the leaky edge. The problem is, in part, that the dripping edge does not leak. It may have been too tight when installed, causing it to lie too flat. It's not really a drain problem.
The fact that rainwater ran through the fascia was a problem that needed to be solved anyway.