You are correct, what I meant to say was the maturation and universal adoption of the trap.
Not everyone used it until they realized that it produced more “competitive” results with more meager talent, then when it became universal, it killed the game (for me, at least)
And hey...Boston used it more than anyone.
This is why Montreal was so dominant back when they played the neutral-zone trap to perfection. The 1976-77 Canadiens, for example, were arguably the best team of all time. They finished the season with only 8 losses in 80 games (60-8-12), and outscored their opponents by an unbelievable 387-171 margin. Their individual award winners included Guy Lafleur (Hart, Art Ross and Conn Smythe Trophies), Ken Dryden and Michel Larocque (Vezina Tropy), and Steve Shutt (led the NHL in goals scored, though this was before the NHL adopted the Maurice Richard Trophy for this). They also had first-team NHL All-Stars at four of the six positions in hockey (Dryden in goal, Lafleur and Shutt at both wings, and Larry Robinson on defense). Larry Robinson was an unbelievable +120 that season -- the only player other than Bobby Orr to finish a season with a plus/minus rating over +100.
And yeah, they played the neutral-zone trap.
What changed in the 1990s is that teams played the trap as a defensive system but simply didn't have the scoring talent to play the counter-attacking part of the system very well. The post-2005 rule changes have helped add offensive excitement to the NHL, but there still isn't enough real talent to fill the rosters of all 30 teams. Even during those dismal years there were a number of teams that put very talented rosters together, and they played exciting hockey while winning championships. I'd cite the Colorado Avalanche and Detroit Red Wings of that era and the 1999-2001 New Jersey Devils as good examples of this.