The common factor in all failed rebuilds is when you can't develop either a #1 goalie or d-man.
You can't even talk about center depth look at Nashville - they have never had a number one center, even the Oil back in the day only ever had Weight, then finally had Comrie for a year.
You also are right you can't have 18 year old's be part of the leadership. Though guys like Horcoff/Moreau probably weren't the greatest leaders. If Jason Smith hadn't broken down so early he would have been a great guy to have around Hall/Eberle.
He just kept people in check. Even Souray (unfortunately that's another topic - and unfortunately people don't know the true guy so no point in going any further).
I think Horcoff (who Hall, Ebs always speak highly about) and Moreau were great leaders... not sure why you are contrasting Gator? He too was broken down, but don't think these kids didn't know who these guys were. They would have been early teenagers when 2006 happened. They would have watched every game.
The issue, IMO, was 1) leadership was ALL that they could provide by the time Hall and Ebs were here, and 2) Horc, Moreau, Gator, Pisani... all grew together as a core of well-coached guys who played low-event, low-mistake hockey. They needed that precision to have success... and I think it caused young vs old friction given that the young guys were depended on so much for offense AND expected by the vets to not make mistakes. The vets, for their part, were well aware of what was needed to WIN and frustratingly still holding onto dreams it would happen in their career timeframe... probably didn't realize that 2006 was going to be their only chance.
You know... that 2006 run and the Pronger trade was a heartbreak that few from that era (incl esp Lowe, Moreau, Smith, Horc less so, but... others) properly recovered from.