In his new book “Welcome to the O.C.,” Rolling Stone’s chief television critic, Alan Sepinwall, provides an oral history of a cultural phenomenon that became an example of unpredictable success. Despite many shows featuring attractive casts and glamorous California settings, “The O.C.” managed to stand out — and change the formula for television teen dramas. Its story offers insights into the cultural context of California and Orange County in the early aughts and underscores the elusive nature of hits in entertainment.