It was a lot easier for LA to get to the finals in the early to mid 80's than it was for Boston and Philly, unlike today, where the West is where the power is, back then the more of the elite teams were in the East.
It was so hard for teams from the East to even get to the finals, they were tired and exhausted and end up playing one of the fastest teams in the history of the game, who wouldn't even give you a chance to play defense.
Today the Spurs are the monster of the League and while the other teams in the West are far better than in the East, none of them are close enough to give the Spurs a tough test, or even begin to wear them down.