>I am irritated by the weak justification though
Pot, kettle.
>Humans evolved the ability to eat meat because it increased their chances of survival in a hostile environment with scarce resources.
It doesn't stop there. Humans have subsequently evolved to thrive on fatty foods. Our understanding of nutritional evolution is incredibly weak. Despite agriculture predominantly giving us access to carbohydrates, human brains are mostly fat-adapted. Many of today's health epidemics are linked to a lack of fat and an excess of carbohydrates. Try finding fatty fruits and veggies: they were incredibly scarce for most the human population until the last 100 years. Several people have noticed significant improvements going predominantly meat. There's more going on here than just the scarcity argument, the scarcity argument is a gross simplification.
>Comfort is the only reason why healthy people eat meat
No. Plenty of people are eating meat to be healthy. People are, in fact, getting frustrated by listening to the advice of the average western diet, listening to dietitians when they get fat, and unable to get in shape despite putting in an insane amount of effort listening to their dietitians putting their hormones out of whack, making them hungry and agitated 24/7, while they keep saying "just keep going". We don't process meat-based products the same way we do plant-based products.
This is not to moralize meat. Rather, this is to indicate people jump on the "meat is bad / lazy / immoral" bandwagon way too quickly, being spoonfed the common narrative without doing an ounce of research and frequently without experience. Just like the average person doesn't eat meat for any other reason than their own comfort, so does the average person stop eating meat because everyone and their mother claims eating plants will save the world. It's becoming a story of "my propaganda is better than yours".