I am curious to know what you mean by authenticity? Both of these guys are no longer young and right or wrong to stay relevant you HAVE to stay with what is current (fashion, rap style, etc).
Me personally, I have never liked auto tune used a lot in a song except for Roger and Zap. Nor do I like the Future style of rap delivery that everyone is using right now. However for all intense purposes the people have spoken and that is what is hot at the moment. You will find that style of rap and auto tune can be found in other genres right now.
If you want to be successful in your craft you need to stay current. This applies to practically any field if you want to make it a career.
Good thing for me is, I don't have to dress like a teenager in order to play the role of being considered "current". I am too damn old to be dressing like that anymore.