Since 1967-68, when six teams were added to make the NHL a 12-team league, there have been a number of playoff formats: division-based, conference-based, and for two seasons (1979-80, 1980-81) the top 16 teams were seeded by regular-season points.
In none of those instances had the top two teams in each division or conference, or the teams with the two best records, been eliminated in the first round of the playoffs.