For each position I had 3 players, who where all capable of starting important games. Besides that, players for other positions, where capable of playing second and even third positions. So even if 3 players of the same position where out the same time, I still could field ea decent team.
It's all about building a balanced team, with enough players. It's not just good for injuries, it also helps with tactics.
We are 50.000 users on the game, so 50.000 deferent ways of thinking. I didnt saw any team to be very successful with what you are suggest. Great players win the games, and since we are talking talking about the NBA too, just look the Denver. They have the greatest dept in the NBA after Melo trade, they won a lot on the regular season, but they luck the go to guy, and on the PO are strangling.