I think most of us think it is possible to live healthily as vegetarians, but much more difficult. Meat from other mammals contains almost all the nutrients we need in a convenient and properly balanced format. In particular the protein quality and digestibility is higher than in most plant sources.
For those of us who are active athletes, there are a lot of anecdotes about people who tried vegetarian or vegan diets and found they had trouble recovering from workouts or healing from injuries. I suspect many vegetarians suffer from subtle, sub-clinical nutritional deficiencies
and that makes me hesitant to give up meat.
There are around 300 million vegetarians in India. That is close to the population of the United States. Whatever health problems you think they may suffer from it isn't the ability to procreate.
I gave up meat 6 years ago. All of my non subtle clinically diagnosed health problems went away.
I did it because I couldn't think of killing animals anymore and the wonderful side effects of obesity, high blood sugar, and high blood pressure all went away.
Most of the benefits you mention come from weight loss, and almost any intervention that can cut weight during the first years would report similar improvements.
Plenty of people lose weight, drop blood sugar and drop blood pressure by going keto. And some with a more extreme carnivore diet.
The real comparison here would be to have "2 people like you" 6 years ago and have two interventions. One going vegetarian and another going keto or carnivore, and see where there are now.
There's more to life than procreation. How many of those 300 million vegetarians are still able to perform at a high level in strength and endurance into their 50s and 60s?
Assuming equal caloric intake there is no reliable evidence that eating meat increases obesity, blood sugar, or blood pressure. Rather the opposite.
I post this hesitantly because it's probably some subtle bias (possibly selection/observation bias), but: the vegetarians and vegans I know personally, they all look borderline unhealthy and seem to lack energy in a subtle ways. Also, my wife sometimes watches cooking vloggers, and I can usually tell at a glance whether the particular tuber is a vegan/vegetarian blogger or not: the ones who are also give this impression of health problems and lethargy. This observation makes both of us hesitant to go vegetarian (though we try to reduce the amount of meat we consume).
For those of us who are active athletes, there are a lot of anecdotes about people who tried vegetarian or vegan diets and found they had trouble recovering from workouts or healing from injuries. I suspect many vegetarians suffer from subtle, sub-clinical nutritional deficiencies and that makes me hesitant to give up meat.