At a personal level, those advocating the move from meat and animal product free diets completely fail to take into account the problems of people with food allergies.
Many food allergies are plant based and if you have already voluntarily restricted your diet by excluding all animal based products and then are allergic to soy and all nuts, both listed in the top ten allergens, then you are going to be limited to a very restricted diet, with a problem getting sufficient proteon.
I said at the start that this aspect of the issue is personal, a member of my family has been diagnosed with an auto-immune disease, In the last few years they have developed allergies, to soya, nuts, fresh fruits and several other plant based foods, and needs to carry an epipen allthe time because their reactions can be severe.
Exactly how could someone with those allergies eat a balanced vegan diet? As it is because they have few allergies to animal-based foods, dairy, eggs, fish, meat, they eat a varied, nutritionally balanced and enjoyable range of foods..
I appreciate other people have allergies to animal based foods, but very few people are going to have allergies that extend extensively across all main protein foods, whether animal or plant based.