The “veganism is a cult” or “veganism is dogmatic” dismissal is about applying different standards to minority behavior. You feel empathy for dogs & never eat them? You are a normal, decent person. I feel empathy for cows & never eat them? I am absolutist, dogmatic, cultish, and lack the capacity or humility for nuance.
This double standard serves to maintain the status quo by delegitimizing instead of engaging with any challenge to it. And the challenge, again and always, is this: how are cows and dogs different? On what criteria are you basing your different treatment of these two animals?
If there is a criteria, it should be openly discussed. Instead, discussion is usually shutdown. And if there is no difference, vegans are not more dogmatic than any other homo sapiens who excludes certain animals from their diet. In fact, they are less so. The insistence that one animal is food and one is friend and that the foundation of this division can never be the object of dialogue is the dogmatic guarding of social norms.