Veganism depends on cities and industrial mass production
Pulses, grains, vegetables, nuts and fruit are farm foods, grown in the countryside. The one real dependency is B12, a single bacterial supplement, and most B12 made today goes into animal feed. Rejecting industrial food systems is no argument for meat over plants.
A diet that only works with factory-made supplements and long supply chains belongs to the same industrial system that gave us intensive farming, and I don't trust that system. I want food a rural community could produce for itself, close to the land, and animals have always been part of that. Veganism looks like an urban diet that depends on the very mass production I'd rather leave behind.
A plant-based diet is about as rural as diets get. Beans, lentils, oats, potatoes, brassicas, nuts and fruit are grown in fields and gardens, and most can be grown, stored and cooked with no industrial input at all. Mass production is not what makes them available. Supply chains bring them to cities, but they bring meat to cities too, along with the slaughterhouses, refrigeration and transport that meat needs.
The real point is B12. Plants don't reliably provide it, and a vegan diet needs a dependable source. That source is a supplement or fortified food, made by bacterial fermentation in a factory. This is a genuine dependency and shouldn't be waved away. But it is one nutrient, one small tablet, not a whole system. And modern livestock depend on the same industry. Much of the world's manufactured B12 and cobalt goes into animal feed and mineral licks, because farmed animals in modern conditions often wouldn't get enough otherwise. Meat from a modern farm, even a family one, usually carries that supplement inside it.
If you really were living self-sufficiently, cut off from any supply, the standard definition of veganism already allows for that: 'as far as is possible and practicable'. Few people making this argument live that way. Most can buy a tablet as easily as a steak.
Disliking industrialisation is a coherent position. The industrial system's most direct product in food is intensive animal farming, which you already reject. Small farms do raise animals with less suffering than intensive units, and that difference is real. But on the gentlest farm the animal is still killed young when it didn't need to be. Leaving cities behind doesn't make that killing necessary. Plants grown on the same land would feed more people.