It's like saying; "Why do people order Pizza or eat at restaurants when every home has a stove?" or "Why do people buy vegetables at the market when it's so easy to grow your own?" Different priorities. Different talents. Different lives. Just another facet of the magical diversity of human experience and expression. If everyone had to re-invent the wheel every time they needed to go to the store, it would slow things down considerably. The streets would be more interesting, but a lot of people couldn't get out of the driveway. Everyone is different, thinks differently. For instance I have difficulty understanding why everyone doesn't realize such a simple thing without asking about it, but that's probably just me. Just my 2 cents worth, opposing views encouraged, expected, and met with blank incomprehension . . .