It's quite simple... because that is how they designed the game. It is not a bug. As for the logic behind why they did it that way... I have no idea and it doesn't really matter. The original creators of the game made it that way so D11 was following the original design of the game. It's been that way and more than likely remain that way. I know that in the early stages of the game the number of capacitors was limited so be glad for what is available in the game now.
The way I deal with it is I grid out the entire map (usually large ones) into 4 sections with the center lines being 2-4 blocks apart then I grid them out into 14x14 blocks as the power lines will only cover out to a max of 15 blocks away from the nearest power line. During the early part of the game when I can only afford 1 or 2 power stations I just link the 4 sections together with 1 line each in the center so I know where it is. That way there is only 3 or 4 links to be removed to turn it into an individual grid of its own later when my current power station(s) get overwhelmed and I can afford to add another station and capacitors.
