Why does a Rack application need to be an object and not a class?

Question

ruby

All introductions to Rack emphasize that an application should be an object, not a class. Why? After all, this code will work:

class MyApp
    def self.call(env)
        [200,{},["text"]]
    end
end

Answer 1

The application must respond to the "call" method.
So both MyApp.call and MyApp.new.call are valid