Which is why "at least nothing had to die" as an argument falls apart pretty quickly as a reason for eating Beyond Meat burgers. Pretty much everyone has different lines on which animals they find acceptable to kill, and I don't think that most people care too much if an animal that has been bred specifically to be eaten ends up getting eaten. If people want to try the sympathy route to get people to switch to a plant based diet, I think they'd have better luck bringing up the poor living conditions frequently found in factory farming.

True, however proponents for animal cruelty don't often* factor in the destruction of natural biodiversity, and generally only care about the 'big' animals that they can 'see'.

*Edit, removed the blanket generalisation. I know a lot of people do care about broader biodiversity, it's just not quite as commonly seen.

There is only so much natural arable farmland on earth. If everyone is vegetarian, I'm not sure it would sustain current populations, without requiring deforestation/etc. There are many places in the world where people are sustained by animals like cows and goats which are able to eat things humans can't digest on their own.