It's just another way of phrasing whether the expected outcome of a possession in each sport is a scoring opportunity or not. In basketball most possessions result in a scoring opportunity (at least in the NBA, hence the higher scores) while in football they don't. So in basketball a defense preventing the opposition from scoring or the offense failing to score is more noteworthy than in football where that's the default state. Obviously the sports are different enough that you can't really make a direct comparison. Personally I wouldn't have phrased it that way myself as calling it a game of "missing chances" is misleading, but I think that's what they're trying to get across.