Why are the values in a box? come out of there.

out-of-the-box.cs

private static class Boxed<T> {
    internal static readonly Converter<object, T> PleaseComeOut = Boxed<T>.Delivers(typeof(T));
            
    private static Converter<object, T> Delivers(Type type) {
        if (type.IsValueType) return new Converter<object, T>(Boxed<T>.Contents);
        throw new InvalidOperationException("No thanks");
    }
    private static T Contents(object value)     { return (T) value; }
}