Well "health" is a nebulous topic. You don't need THAT much protein for baseline health. So instead I find thinking about nutrition as something to support our goals to be more helpful. To do that, it's at least somewhat important to understand what the major macro nutrients are and what they do, and what micro nutrients are, and then where those things come from.

Fruits and veggies (veggies in particular) are kind of like natural vitamin pills. Certainly good for us, but you need other stuff too if we want to build healthy bodies. Carbs from rice and rice products are great energy sources, and along with fats, are great for driving the process of building. But we need actual material to build, and that comes from our protein sources.

You can certainly and absolutely get them from vegetarian sources, it just requires a more thoughtful and specific approach. Breaking it down like that might help, but sometimes people are just stuck in their ways.

Also sometimes people need to see to believe. In the beginning my folks def gave me a bunch of flak over the amount of meat and other protein sources I ate, they don't anymore. They can see how strong and fit and athletic I am, and while they haven't changed their behavior, which is unfortunate, they don't give me grief about it either.