Steve Jellinek, a vice president of commercial mortgage-backed securities research at Morningstar Credit Ratings, sums up the attraction of grocery-anchored retail in four words: People need to eat. It’s more complicated than that, of course. People also need to wear clothes and wash their hair and buy mattresses, after all. But while grocers aren’t entirely immune to the trends buffeting the larger retail world, there are reasons to believe the sector’s brick-and-mortar business will prove resilient in years to come.