Right. Vegan diets avoid animal suffering. Vegan diets make more efficient use of land since you can take the 7,000 pounds of vegetables and grains required to yield 500 pounds of beef or pork and just feed the 7,000 pounds of vegetables and grains directly to people. And breads, pasta, potatoes, rice, and legumes are some of the lowest cost foods in calories per dollar.

Those are genuinely compelling reasons to promote a high carbohydrate vegan lifestyle for everyone. But again, your example and some others stand in a strong contravention of it. I've heard of low carb vegan diets, but I imagine it's difficult.

This was the first hit I found on a web search for low carb vegan, and a lot of the listed items look okay https://lowcarb-vegan.net/vegan-keto-diet/ - but for example my sister is vegan with celiac disease (cannot have gluten) and allergy to soy. So all of the food options from wheat and seitan or soy and tofu or low carb tempeh wouldn't work.