We’re actually omnivores, I get your point though, eat meat and you’ll be in much better health in my opinion.
I think that we are on the same page. We are omnivores to the point that it is unhealthy to exclude most food groups. I am old enough to have known many vegetarians for many decades and for most it appears to be unhealthy in the long term. Most young people can get away with it for a few years then bad things start happening.
The negative results for people who eat nothing but meat are also quite obvious after a few years or sometimes a much shorter period of time. And let's not forget people who exclude fruits and vegetables from their diets or whole grains. Most of the unhealthiest people I know claim that they are gluten intolerant...
I don't know why any of this is the case. But I suspect it is because maintaining a healthy gut biome is very important to our well-being and variety is one of the best things we can do to enhance this. The mechanisms are still not well understood but good health typically results from good digestion along with vigorous physical activity. The best diet in the world is not going to do much for your health if all you do is sit around all day.