A demand for the average American to eat more meat would have to explain, as a baseline, why our already positive trend in meat consumption isn't yielding positive outcomes. There are potential explanations (you could argue increased processing offsets the purported benefits, for example), but those are left unstated by the website.
[1]: https://www.agweb.com/opinion/drivers-u-s-capita-meat-consum...
[2]: https://ers.usda.gov/data-products/chart-gallery/chart-detai...
(Note that I am neither a vegetarian nor a vegan.)
Because of old age. Being vegan increased your odds threefold to die of old age instead of prematurely from disease.
Apologies for not having a link to the source