The point of the GP is that that full understanding can't happen in a human brain, but reductionism may be a lever good enough for that human brain to use.

>> do we need to emulate the full process?

Probably not, but let's assume 'yes'. It seems likely that it would possible to optimize the emulation to a point where it becomes practical. We do something similar today with weather simulations; it's not possible to emulate each molecule in the air, and yet meteorological models manage to account for an insane amount of processes and--short term--produce accurate predictions.

In a more subjective note, I believe the methods and ways of thinking in biology need to shift from "let's understand everything" to "let's produce a forecast and maybe fix some stuff". Pharma companies are already in that track, but it could be that the general public and people in academia are still in the full-complete-very-detailed-understanding wagon.