You can try to misconstrue and ridicule the argument, but that won't change the math that if you have one thing that causes 1 unit of damage, and another thing that causes 100.000 units of damage, then for all intents and purposes the thing that produces 1 unit of damage is irrelevant.

And any discussion that tries to frame them as somewhat equally important issues is dishonest and either malicious or delusional.

My guess, as I've expressed earlier in the comment chain, is that it's emotionally easier for people to bike-shed about the 0.01% of their environmental impact, than to actually tackle things that make up 20%.

And no it's not only beef (which is a stand-in for meat and diary), another low hanging fruit is also transport, like switching your car for a bike.

But switching from meat and diary to a vegan diet would reduce up to 20% of your personal environmental impact, in terms of CO2.

And about 80-90% of rainforest deforestation is driven directly or indirectly by livestock production.

So it's simply the easiest most impactful thing everyone can do. (Switching your car for a bike isn't possible for people in rural areas for example.)