For those wondering, the ratings for Nitro didn't take a big dive until deeper into '99. That is also peak Attitude Era. So there's a couple things going on. WCW didn't push their younger talent but WWE did. Really, WWE had no fukking choice but they did and Austin/Rock became household names.
So while it was the booking in WCW that was a huge problem, it was more so that WWE had the fresher crossover stars. I think the fingerpoke was definitely awful but with WCW you can't just pin it on one booking decision. It's a combination of things. The booking will always be the biggest talking point because it got so bad and stayed bad until maybe 4-5 months before they close shop.
People forget that WCW was getting decent again for a few months before they sold.