It seems that the additive layer manufacturing technology extends not only to plastics, but laser-to-metal as well.

If this is the case, what is the purpose of having/learning so many different variations of CNC machines?

Isn't 1 rapid prototyping machine that can print metal (despite it's ridiculously high cost) is enough to create anything from any angles?

Or is there a limitation to these rapid prototyping machines and we require different CNC machines still?

Also, robotic arms with custom routers seem to be able to cover many angles. Although I realize it fails in precision work.

What then is the ultimate setup that can cover every angle of process and you can literally make anything?

1 rapid protyping machine
1 robotic arm
1 engraving machine

???

I've just begun learning CNC, and was pondering what the ultimate thing would be to reduce time in manufacturing while having all the possibilities.