They did it to Kennedy and did it to Nixon. Remember, after Hoover's death, Nixon intended to reign in the FBI. Mark Felt, Associate Director of the FBI, did not like this. Hoover died on May 2, 1972. The Watergate break-in occurred on June 17, 1972. Nixon did not know about the break in.
Felt force fed information to Woodward and Bernstein (he was the "deep throat" that gave them all their information.) Woodward and Bernstein were NOT great reporters. They were mouthpieces for the deep state. Nixon resigned over the cover up, and the FBI continued. Considering that Manafort was most likely planted in the Trump campaign to create a crime that could be traced back to Trump, I've often wondered if they didn't do the same thing to Nixon.
No matter what though, never forget that Nixon getting shafted was not because of great investigation by reporters. It was the deep state going after Nixon.
They never got over Nixon's victory over Helen Gahagan Douglas for California Senator in 1948. Watergate was the payback.