It’s very complicated to eat plant based proteins properly. There’s so many “gotchas”, if you don’t get it right and keep eating that way for a long time you’ll do serious damage. Better to just eat good animals.
I think there are - might be misrembering - more credible studies that you can live on a diet of exclusively potatoes without ill effects aside from, well, that kind of diet itself.
I looked over the article and was expecting to see something on it like "Funded by [Tuscany's version of the Beef Producers Council]."
There is no diet for everyone. All diets are fundamentally dictated by our genetics.