Yep. They were lucky enough to have an incredible cast of talent back then. Stone Cold was absolutely an important part of those ratings, but it was also important that when he dropped out there were others that could easily carry the weight.
Regarding the ratings: I fall perfectly into that 18-34 bracket that's in heavy decline (assuming those figures are still semi-accurate today), and it's because there's no option to stream RAW and Smackdown. If they were added to the WWE Network, even with a 24 hour delay over live broadcasts, I'd watch them. But no way I'm paying for a Sky TV package over here just for WWE. Over-priced as hell, and their continued reliance on cable TV when it's been dying a slow death for over a decade now is the biggest reason for their audience loss imo.