I do suspect that some of those 5, 6 and even 7 liter engines also warrant fairly beefy radiators. Like the Ford F150 is available with small engines from 3 to 5.2 liters and has a lower grille, but the super duty that has a ridiculously tall grille gets either a 6.7 liter diesel or a 6.8 or 7.3 petrol... And you know the diesel crowd likes to tune them too, so those need a lot of cooling to cope with those stupid ass coal rolling remaps (those tend to raise EGTs quite a bit, meaning your turbo runs even hotter, so now you have to cool down the charge air and engine oil even more).