What about after 2002? They lost House seats and their Senate majority all under a Republican President who had lost the popular vote and was presiding over a weak recovery from a recession. They would be out of power for four years...the only time in the post-WW2 era they would be out of power for more than one cycle.
1984 was a time where the Democratic Party came to recognize that they had nowhere near enough Grass Roots support to win the Presidency. They had no "base" of states they could count on, having lost 49 states twice in 12 years.
They didn't even win the Senate back. They controlled the House only because of the remnants of the Conservative Southerners, and (unlike 1972) some of those seats were lost in 1984.