I understand your concerns. however, the rule is a bit different when using 24V instead of 12V (You will be surprised..).
This is why you will find at E3D store "only" 400w 24V 16.5A power supply (for example).
I have found a nice post that explains abit of it much better than I probably could.
Also, notice that I assumed that each one will probably pick his own parts/components so i mentioned it as a note.