I suppose there are two factors in play - one is what the coach wants to do and two, the personnel he has at his disposal.
There was certainly a trend where teams wanted to have halves play almost the same game - and split in attack. What Ricky Stuart was doing with George Williams and Jack Wighton for the Raiders was players playing an almost identical game split left and right. Whereas now he has a much more traditional pair in Jamal Fogerty and Ethan Strange.
But again, did Stuart do that because that is how he wanted the Raiders to play or because he saw that neither Williams or Wighton were traditional game management half backs and so he wanted to share the responsibility.
With all these things, the devil is in the detail but my general point is that when you see half backs like Reynolds, Hynes, Cherry-Evans and Cleary playing a very traditional scrum half role both sides of the ruck (and 4 of the top 5 sides) the idea that halves split left and right is nowhere near as prevalent as it was maybe even a few years ago.