This is true. Most of the potatoes eaten are valuable in caloric-deprived situations, but they are not a long-term healthy food due to the thrashing they do to insulin management.
That is misleading. Potatoes are ranked as one of the most satiating foods per calorie. The problem is people put a lot of butter/oil on them. Or eat them too processed.
I've been reading that what gives potatoes a satiety boost is that they contain proteinase inhibitors. These limit your appetite by disrupting your digestion. Maybe they are more effective as a weight loss food than the raw nutrition numbers would suggest, but for an athlete that wants to cut I don't think slowing your ability to digest amino acids is a good idea.