At the height of Nixon's 1972 re-election campaign, individuals broke in the Democratic Party headquarters located in the Watergate complex in Washington DC and planted listening devices. They copied documents. The burglars got away with the break-in for weeks. It was only after they made a mistake while retrieving the bugs that they were caught.
Over time, the caper was discovered and the ensuing cover-up resulted in the resignation of the President of the United States. Several of Nixon's top aides, including the Attorney General, head of the Committee to re-elect the President, The President's Chief of Staff, the President's Counsel, and a whole gaggle of assistants, advisers, and aides were convicted of crimes.
Nixon won the 1972 election handily. There is no evidence the information gleaned from the break-in contributed to the election results. By the time the cover-up and scandal hit the press, the event was long past.
Hillary Clinton was an aide in the subsequent Congressional investigation of Richard Nixon and the Watergate affair. Do you think at any time Hillary Clinton or the Democratic Party would have accepted a terse "It is over, what difference does it make?" from Mitchell, Haldeman, Erlichman, Liddy, Hunt, Colson, Dean, or Nixon?
Watergate was a botched, third rate burglary. No one was hurt, no one died. Mrs. Clinton and President Obama can not make the same claim about Benghazi.