His 1974 season with Lotus is the one that gives me pause. He was teamed with Ronnie Peterson, who managed to win 3 races with the (relatively) ancient 72, while Ickx couldn't win a race. As good as he was in F1, I still think that his real prowess was endurance racing. The same was true of Pedro Rodriguez and Jo Siffert.
Legend also says that Prost was having issues with his brakes, so he would have retired from the race, thus losing the title by 5 points ...And, so the legend goes, he's also the man who cost Prost the 84 Championship by doing Prost a favor and red flagging the 84 Manaco GP resulting in half points being awarded and thus Prost lost the title by half a point.
If you look at the amount of rain that was falling, that race wouldn't have gone on much longer. It was absolutely chucking it down.
I'd add Olivier Gendebien to the list
Legend also says that Prost was having issues with his brakes, so he would have retired from the race, thus losing the title by 5 points ...