The only champion that is allowed to do hybrid damage and true damage and dish out DPS was traditionally Kog'maw. That was because he was unbelievably immobile, weak early and has a specific buildpath with a huge price tag so he won't get out of control. (Unless buffed by a enchanter)
...Just why is Kai'sa able to bypass nearly every weakness Kog has aside from range and be fine with it? To me this champion is far more problematic than Yasuo/Irelia/Akali like anyone would rant about. You cannot build against her, she is really hard to shut down and does not have a defined weak phase. Like why would you NOT pick her. She is 32% pickrate which is 10% higher than Lee or Ezreal which goes even higher if you go up in tiers (39% in diamond). You just created a "must pick" champion.