Out of curiosity, what would make Lua valuable to add in browsers by default? It is similarly prototype-based, has the same closure design, is dynamically typed

Out of curiosity, what would make Lua valuable to add in browsers by default? It is similarly prototype-based, has the same closure design, is dynamically typed, has an object system fairly similar to JS (with the type of arrays and hashtables both mixed), and its number system is also based on floating-point numbers… I honestly don't see how we can justify the cost of adding Lua to browsers. I see the merit of Lua-to-JS compilers (existing codebases or sheer love of the syntax), but built-in?