It's because they are financially able to retire before ever stepping foot on an NBA court, and the coaches are pretty much subservient to the talent. There are a few token counter-examples but only a few. Of course there were worse eras and the technical aspect of the game is far and away better than it's ever been, with even mid level guys being very talented technically. guys in the 80's could barely dribble and run, and those who could were superstars.
Imagine every football player makes 20 million for a 4 year contract, at least. Now imagine the deals they have with one another to not kill each other on the field. It would be flag football. It's flag basketball.