This feature occurs in for example : King of Thieves.
Being able to test your own defense without rank points or loot should be possible. you could also use it to kill time since half The time atleast you are just waiting for your energy.
Is Hel better than Justice in The middle? I wouldnt know cuz i cannot try it out
And to be able to try out alliance members defense would also be Nice mainly for The fact that we only kill titans together, we could give eachother help through trying out instead of guessing based on a picture with stats
That is all, thank you for reading!