> 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.

Well the answer to that is to eat more fat.

I ate only keto for years and I'm getting back to it now so I have some experience to speak of.

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.

If you are talking very specifically about a ketogenic diet, then fruits actually do have too many carbs to maintain ketosis. In that case, it isn't some irrational fear, but reality.

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.

Fruits, yes, because it will kick you out of ketosis. Fiber, every keto adherent I knew would eat fiber in reasonably large quantities because keto often causes constipation, and a lot of the substitutes for things with "regular" carbs were high in fiber.