So an engine failure on a 747 wouldn't have resulted in a diversion, then ?
Not necessarily. With 4 engines you're legal to continue to destination.
A extreme example of that was an British Airways 747 that shelled an engine taking off at LAX and continued on toward Heathrow. Now they had to divert into Manchester due low fuel, so it might be wise to give your OEI performance charts some extra scrutiny before launching across a big cold ocean. But the point stands that it's not a mandatory divert to the nearest suitable airport as it is in a twin. You might at least be able to stagger on to a place with hotels.