Many consumers think they can substitute chicken for beef and make a meaningful difference in their dietary footprint. Not so. ... When it comes to lowering the costs of mitigating climate change, the study shows that a diet devoid of ruminants would reduce the costs of fighting climate change by 50 percent; a vegan diet would do so by over 80 percent.It actually seems to me that cutting the cost of fighting climate change by 50 percent is making a very "meaningful difference."
Of course, it isn't the biggest difference we could make. But no one is able to optimize their life to absolutely make the biggest difference. More importantly, as Nobel Laureate Herb Simon pointed out, people rarely make any decision based on what is optimal. Rather, we act on what is better, what is "good enough."
And when it comes to health, water usage, global warming, and other impacts, chicken is almost always meaningfully "better" than beef. Unfortunately, this makes chicken "good enough" for most people in most situations.