I dont see why retreat be punishable at all, I mean technically what is the difference between retreat or simply reloading? only that in one option you see that loading screen after the party wipe and on other you start retreat right away and get same result.
Let people to play game as they want to and how they want to.... I mean even if they want to play it alone on "kings throne" and play it instead of mobile, let them.... it is their and only their`s choice