I know the kind of people you mean, and certainly we have the "all or nothing" types among us. I generally view this binary, black and white thinking as immature, and have noticed most people who think in black and white terms come around to some shade of grey--maybe darker, maybe lighter--eventually.
I do believe people generally have the responsibility to not use our words to make others feel inferior. But I think framing the defensible, generally good practice of, for example, choosing grass-fed beef, as "elitist" and then supporting that by characterizing discussions of how to approach a freezer full of bison (or whatever) as "bragging" comes pretty close to begging the question.
In my experience here on PH, I perceive a more thoughtful tone most of the time--paticularly when dealing with new people and people with financial limitations--and true elitism and bragging relatively rare. But perhaps I'm one of the elitists and just can't see it.
I'm a member-owner of a small, very nice local food co-op that emphasizes natural, organic, local products. Most of the farmers whose products stock the shelves also appear at our neighborhood farmer's market in the summer. You don't have to be a member to shop there, but I invested to support the enterprise, because I have principles like supporting local farmers, rational and sustainable farming practices, and the humane, ethical treatment of animals.
I view this more as my personal responsibility rather than worrying about the responsibility of (or for) others. I have enough trouble keeping my own house clean, and sometimes I compromise. When I compromise and buy a CAFO ribeye for $10 at the supermarket because it would be $16 at my co-op and I don't have $16 that day, the shopper next to me buying 4 lbs of hamburger for the same price could say I was elite. And the one further down the aisle getting 8 pounds of chicken thighs might think we're both elite. We're all elite to the person who still has a week to go before they can visit the food pantry again.
Maybe "elite" isn't the word we're looking for, but "privileged," or "more affluent," or something. We do live in a world of people with different means. Those of us with more have more choices, and we can use those choices all kinds of ways.
The food at the co-op costs more than that at the supermarket--our little operation certainly exerts much less influence over the market than Whole Foods or Safeway. On the other hand, I can walk there in 3 minutes, instead of driving, and it's so convenient (not to mention socially rewarding, as I have a personal relationship with our team there).
I know it might be difficult to feed a family at the co-op, but I'm not feeding a family, only me. I have a modest income, but I can afford it. I'm lucky that I can manage life without owning a car, and that represents thousands of dollars I can divert to qualify food. I also don't pay for television, and live in an extremely small and perhaps less than luxurious apartment that while nice and cheap, also lets me live steps from the co-op, the library, and multiple modes of public transit.
These all represent choices I made, some conscious and planned, some happy coincidences. All of these mean I can afford to use my dollar to NOT support factory farming and the CAFO system, and instead to support local farmers. I'm not exactly sure why I want to be good, or at least be better than I am, but I do, so I think maybe I should. Personal choice does matter. My food co-op comprises something like 1,800 people who all could and did make a choice to support a different system. That's just 1,800 people in one neighborhood in Chicago, and now residents have a new locally owned and operated grocery store that can sustain itself and even profit.
A rising tide lifts all boats. Leaving aside the many people who cannot afford to make the kind of choices I've been able to make, if a good number of the other thousands or millions of people who can make such choices actually do, things would be better for everyone. So I think ringing the grass-fed/anti-factory-farming bell as often as possible--and taking the time to explain why--makes sense to me. Some people can't afford it. But some can. That message isn't inherently elitist, and it probably ought to be delivered in ways that don't make it seem that way. Maybe that's really the problem here.