Why buying Chipotle would be a mistake for Starbucks, even with Brian Niccol in charge

If Starbucks bought Chipotle Mexican Grill, a possibility the Financial Times reported this week was being explored by the coffee giant, it would be the largest purchase of one restaurant chain by another ever in the U.S. It would also almost certainly be one of the biggest missteps, given the limited synergies between the two brands, the size of the deal and the potential distraction…