Actually, it's quite possible to grow enough food to feed oneself on a small plot of land, without use of herbicides, pesticides or machinery. You may not be able to eat everything you're used to, but it's possible to survive. I don't know whether it's possible for everyone to do that, with the current world population, but it can be done on an individual basis. And it doesn't mean maintaining and slaughtering a herd of anything; that much flesh consumption is neither practical or sustainable.
The point I'm making, and that I think das_nut was first making, is that consumption of non-animal products also adversely affects animals: it decreases the amount of the resources available and necessary to animals (the land used up to grow cotton for a larger wardrobe than one needs, the impact of mining the metals used to make our gadgets, the land taken up by factories, malls, landfills, the pollution of water, etc.) and the harvesting and use of those resources kills animals directly.
I'm quite sure that a poor woman in a third world country who is using the bare minimum for survival is responsible for (probably substantially) fewer animal deaths than I am, as someone who doesn't eat meat, wear any portion of a dead animal, and doesn't eat dairy or egggs other than trace amounts, but uses considerably more than I need to survive.
Ignoring the effect of consumerism on animals is a lot like ignoring the fact that while vegetarians aren't eating dead animals, they are contributing pretty directly to the deaths of cows and chickens by eating dairy and eggs.
I used to think that concerns about the environment was a separate issue, but thinking about it, you really cannot logically divorce environmental concerns from animal welfare/rights concerns - it's like saying, "I care about animals, but I don't care whether they have air to breath, water to drink, food to eat, or space in which to live. I don't care how many more will die because I want something that's grown/produced halfway around the globe." (And yeah, I'm guilty of buying nonlocally, buying and using more than I need, etc. - I'm trying to work on it.)