There is no boogie man trying to scare people away from broccoli.
I disagree, everyone I know who has been on a keto dietic consumes little to no fruits or fiber. Honestly, I'm not sure how they use the bathroom successfully with such little fiber ingestion.
You are correct, fruit is mostly sugar so no fruits. Some keto adherents allow the occasional handful of berries, but I found that just made me unreasonably hungry later on. Not everyone has this reaction, though.
There is plenty of fiber in above-ground vegetables. And even if there wasn't, it's not like eating only meat would kill you, humans evolved on the plains and/or jungles of Africa where meat was almost all that was easily available.
Re fiber, A significant portion of the population (maybe a majority) doesn't need much fiber to use the bathroom. It seems like this need is a common situation that people assume is a universal truth. Further, fiber can lead to constipation for many people.
Have almost no carbs or any calories, they are basically just water. Like you'd need to eat 1kg just to get 300 calories (less than in e.g. 100g chickpeas).
75% of the calories in broccoli is from carbs, sure, but because the overall calorie content of broccoli is so low, it's still considered low carb.
https://www.nutritionix.com/food/broccoli/1-cup
A 1-cup, 156-gram serving is 55 calories, 11g carbs, and 5g fiber, so is only 6g of net carbs for keto purposes.
It's a devious euphemism that screws the people over the most that should be eating more beans and broccoli (et al).