I'd wonder if the results are down to a newer or more casual minded viewer base? I've never heard of this channel before so that's purely conjecture on my part OFC.

WHM has always been the goto pick for casual healers even when it was at it's worst towards the end of HW. Now it's still pretty simple and straightforward to play and is actually in a good spot. If Sadge wasn't the new expansion job I'd wager WHM would be in first place TBH.