Originally Posted by Andrew R Stewart

It depends. If the chain were just old but not worn out he is misguided. If the chain is worn beyond about 1% (as in measured length) then he's got a good point, although the chainrings tend to outlast the rear cogs by a factor or three. Did he measure the chain wear? Did he test the rear cog wear (we use a Rolhloff device)? Did he show you, on your bike, the worn shapes of the teeth?

As to his suggestion of a new bike I have missed feelings. A new bike is new all over, not just the links and teeth of the proposed repair. This newness will show in both a smoother running bike but as well as allow you to enjoy 30 years of product/feature/function development. One aspect that many don't initially understand is that the dealer wants a happy customer many months later. They will make more money on the repair in the short term but the customer will generally be happier months later with that new bike. That happy customer will enjoy riding more and return for both service and possibly service over the years.

So pick your poison. Andy