Out of curiosity, when you say "full carbon" or aluminum, does that include the fork?
I admit, I am completely out of it regarding modern bikes, but way back when aluminum and/or graphite forks never made it in practical use, because if you ran into something the fork would snap, leaving you going pretty much at full speed into whatever solid object broke your fork.
Steel, on the other hand, bends, and absorbs a lot of the energy from the impact. You might still hit whatever your wheel hit, but more slowly.
Klein added boron fiber on the chainstays way back when for stiffness.