I could see it but I don't know how necessary it would be.At rate the game is progressing now by the time you get to Act 8 you probably aren't using many 5 stars anyway, unless you're speed running or it's a really good champ like Doom, Kitty or Herc that you don't have as a 6 star. Or I guess if you need a very specific counter and only have it as a 5 star. I used a 5 star KP on my 600k alt account for Bahamut just because I don't have the best 6 star skills.
Is act 8.4 or act 9 going to implement a 5* ban?