I heard an interview with a player (I forget who) some time ago who said they were ditched because someone realised they actually offered very little in the way of protection, and all they did was soften the impact in the tackle.
Makes sense. RL players' shoulders are hard as bricks. Taking that in the ribs does a lot more to wear the opposition down than padding.
There were points in the late 80s /early 90s where some players spent the entire game adjusting huge baggy jerseys and awkwardly chunky shoulder padding.
Now they just wear those GPS crop tops.