I think the big deal with rally VS other disciplines is that you can't see what's coming up, and you're reliant on pace notes which are being read to you 5 or 6 corners in advance. That's a serious skill to learn – to be able to work out the optimum speed for this corner, on the basis of how much braking room and how tight the next corner is, and the corner after that etc.
Anyone who's driven something like the Nurburgring on Gran Turismo will know that you can perhaps get away with a bit too much speed through one bend, maybe two, but eventually, you're going to come off.
In contrast, Ken Block and most racers are operating from memory and what's going on right now (ie, other competitors in the way).
As for the Fiesta, I suspect the Ford Duratec or whatever it's currently called is under the bonnet – people have 2 litre non-turbo versions of these getting on for 300bhp. I suspect the floor from another car may have found it's way in too 😆