Just learn basic nutritional requirements and plan your meals to meet them. It's not hard, and there are plenty of plant-based options to do so.
People who cut out carbs completely are stupid. They're the main energy source. Sure, you can make energy from fats and proteins, but you can't replace carbs entirely without consequences like ketoacidosis. Just balance your carb intake with your caloric intake requirements. If you're sedentary, reducing carbs is fine. If you exercise a lot, eat some fucking carbs. You're gonna burn them off anyway.
And any sort of diet that wants to only eat one food group is idiotic. The key to good nutrition is about balance. Fruit is good for you, but if it's the only thing you eat then you're missing critical macronutrients. And meat-only diets are just plain stupid.
But we live in the age of internet disinfo, enshittified education, and social media being people's main source of information. So it's really not surprising that people make dumb choices.