You were probably not alone if the news of Donald Trump’s indictment seemed slightly strange: How could something so big — the first criminal indictment of an American president — seem so small? Mr. Trump was not indicted for his efforts to overturn the results of the 2020 election or for engaging in egregious financial fraud to increase his wealth or even for allegedly obstructing the special counsel Robert Mueller’s Russia investigation, which many once thought was the best avenue prosecutors had to ensnare the former president. Instead, the Manhattan district attorney, Alvin Bragg, a Democrat, and his team of...