The entire "problem" with veganism is that almost anything which starts with such an inflexible moral imperative ends up becoming militant, specifically because that rigidity quickly becomes at odds with more practical and functional versions of the idea.
Like so many similar ethics, veganism doesn't really concern itself with creating a practical or actionable roadmap for how food supply chains can be iteratively modified towards the goal of reducing animal suffering. Militant moralists, in fact, tend to avoid such things specifically because they demand a framework of accountable progress. Demanding radical and unrealistic measures be taken, and then condemning those who express skepticism or hostility of this idea is much easier. Like a religion.