The reason is simple: it has higher protein content than most other place based fast foods.
I'd love to live in a world with minimally processed high protein vegetarian restaurant food (like lots of legumes), but the only reliable place to get this that I know of is CAVA.
Products like Beyond are at least a step up from carb heavy pastas and grains or oily fried vegetables and starches which are the staples of most restaurant fare for vegetarians.