first, you are in the wrong section of the forum.
second, you need power to be somewhat evenly distributed across the chip. usually the center of the chip is the critical area. without stripes all the current would have to flow through the tiny M1 rails across incredibly long rails. that is a no no. this is basic circuit understanding, I mean... current has to come from somewhere. In your house you don't put all your appliances in the same socket, why would you connect all your standard cells to the same 'socket'?