We don’t have the land to grow enough food to feed the world on veggies.
Yep.
Well, we might but the problems is that much of the land is not suitable for growing food crops.
Not enough water, not enough fertile enough and the energy required to do the farming would be huge. It would require a great deal of oil.
And without animals to give fertilizer we would have to depend on mined chemicals and that is really a finite resource.