This is very black and white and borderline incorrect. There's nothing inherently bad about carbohydrates. Eating anything will make you more fat; simple carbs are just easy to eat.
Unrefined carbs like in potatoes and (whole)wheat and oatmeal etc. are not bad; those foods provide many good nutrients and do not cause the negative carb effects you mentioned.
It's the same as fruits containing sugar (which is a carbohydrate actually I think) but not causing the same ill effects as eating the same amount of sugar from Sour Patch Kids (candy which is ~80% sugar by weight).
But without fat it's pretty hard to eat a lot of potatoes; they're just too bland.
That's the thing that everyone in this discussion seems to be missing: taste. There are good reasons to believe that better-tasting food may have physiological effects beyond just being pleasurable to eat [1]. This is not controversial when it comes to other substances but with food it's a much tougher battle.
Unrefined carbs like in potatoes and (whole)wheat and oatmeal etc. are not bad; those foods provide many good nutrients and do not cause the negative carb effects you mentioned.
It's the same as fruits containing sugar (which is a carbohydrate actually I think) but not causing the same ill effects as eating the same amount of sugar from Sour Patch Kids (candy which is ~80% sugar by weight).