Well for something like a starter, of course it's not worth going to the dealership for. And it's not gonna be worth taking a car with 200k+ miles to a dealer either. But when Joe Schmoe's Garage down the block can't figure out the problem, what do they tell you? "Take it to the dealership." For example while I was (briefly) working at a Nissan service department, a guy brought in a Nissan Frontier that was 5 or so years old. He took it to the local mechanic because it was running rough and the CEL was on. It threw a couple codes for some sensors, and the independent shop changed them out and reset the CEL. 200 miles later, CEL was back on. So the guy brought it in to the Nissan dealer. I was a technicians apprentice, so it was my job to basically just to assist the techs. The tech working on it plugged a computer into it, saw the codes and immediately knew it was the PCM. I asked him how he knew so quickly. He said "seen it couple times before, there are two resistors in the PCM for those sensors and they sometimes overheat and short."
So he pulled the PCM, opened it up and sure enough those resistors were fried. So he put a new PCM in it, and the problem was fixed. But had the guy just brought it to the dealership in the first place, he would've had a tech who already knew what to look for, and not wasted time and money on unnecessary parts at the independent shop.