alt Hacker NewsCarbohydrates are sugars (from the first sentence on wikipedia): "A carbohydrate (/ˌkɑːrboʊˈhaɪdreɪt/) is a sugar (saccharide) or a sugar derivative." Saying you need "50-75% of your energy from [sugar]" illustrates why that is a somewhat odd statement. Yes, glucose is much better than fructose, but eating a ton of glucose will still lead to high insulin spikes and inflammatory diseases. Complex carbohydrates are better in that they take longer to digest, not because they're magically different. Vegetables are good for nutrients not because you need their carbs.
GP was talking specifically about calories, not other nutrients. My impression is when a vegetable provides significant calorie content it tends to be in the form of carbohydrates.
You have to get your calories (ie raw energy) from somewhere. If you limit saturated fat to 10% then what's left for the other 90% is (roughly speaking) unsaturated fat, simple sugars, carbohydrates (ie complex sugars), and protein. In terms of long term habits converting protein to calories is probably not a great choice for your health. If you decide to go for complex carbohydrates over various oils then vegetables that provide those are a good option.