I think the implication might have been if you had a serious destructive engine failure you were in trouble with the damage possibly being caused to the adjacent engine.
Taking Paris 2000 out of the loop, Concorde and quite a few engine fires over the years in one form or another and the nacelle centre wall did what is was designed to do. Only on one occasion, at least in the UK, did the centre wall need to be replaced.
In 2003 AF suffered a blade out with no damage to the adjacent engine.