I think the point is that the gains are largely irrelevant. Sure, its great 100 mil less people are hungry, but if you look at the trend, we've gone almost nowhere. Not helped by the fact that, there seems to be a variability of about 50 mil. Why? Are we under-reporting? Are we not addressing the right problem?
If you have variability of 50 mil and only 100 mil gains, its really hard to make the case that you qualitatively improved anything, it could be nothing more than a statistical anomaly (maybe there was more rainfall or less competition from local wildlife), and whatever you're doing is not working at all - assuming you are doing anything.
This is pretty different from 50 mph vs 80 mph - that's a ~40% improvement, and we can point at something to show the improvement.
We have added quite a few billion since 2000, so there's an argument to be made that we are making more food, but the ~1 bil number staying fairly stable to me points to a systemic issue, not merely a problem with food distribution.