This is the all or nothing fallacy mentioned up thread.
1. Plants don't have a central nervous system. They're not sentient and don't feel pain.
2. The fact that something "applies to all animals" doesn't somehow make an action morally justifiable. You're suggesting inaction because perfection can't be achieved.
If you want to minimize the number of animals being killed, it’s probably best to eat the largest ones you have.
If you want to reduce death and suffering overall, sticking to plants only is the best route.
The fact is there are good ways to grow animals and plants, and bad ways, and we should just focus on eliminating the bad ways and allowing the market to set prices on what the good practices are. It honestly wound't be too expensive; grassfed pastured beef isn't too much of a premium, neither is soybean that came from an ohio field instead of a Brazilian rainforest. If subsidizes were eliminated for the mass market operations that damage the environment, and introduced for these sustainable operations, you'd see a lot of self correction in the market to fit these more sustainable practices.
This fails at scale. Feeding our population on large animals requires significantly more plant mass than if we eat plants. Large animals are terribly inefficient at converting plant matter into food.
We will harm fewer sentient creatures if we simply eat plants directly.
At a certain scale though you can graze animals on grass sustainably, building soil structure instead of destroying it.
The environmental movement has a beef with beef but the more I look at it chicken is the problem.
I mean, if we also can't eat plants... there's not gonna be much left to eat.