Caporegime
I've said it before and I'll say it again, Vettel wasn't demolished by Ricciardo. The stats say he was, but in two of the races Ricciardo won, Vettel was ahead, with a team strategy mistake costing him one victory and a safety car coming out immediately after he'd passed pit entry the other. That one was particularly harsh as Ricciardo was miles behind him at the time, but was the first able to pit and he duly took the lead when the drivers ahead of him pitted the next lap.
Ricciardo beat Vettel in 11 of the 14 races they both finished, and out-qualified him 12-7. This wasn't a case of Ricciardo getting lucky in a couple of races where Vettel didn't; it was a case of Ricciardo being head and shoulders above him over the entire course of the season. The three wins that Ricciardo got to Vettel's zero, and the 8-4 lead on podiums reflects that. Not only that but Ricciardo did it on only his third season coming into the team where Vettel had firmly established himself on the back of four consecutive world championships.
The idea that Ricciardo didn't spank Vettel in 2014 is just plain counterfactual, and I amazed anyone who watched that season could say otherwise.
I'm not sure anyone expected Ricciardo to take the fight to Vettel, but that was as much about the 2014 regulation changes as anything in my opinion. Vettel was unmatched in the exhaust-blown diffuser era - no other driver had the confidence Vettel had and it was a sight to behold, despite us all hoping his relative dominance would be challenged more often. Even his own teammate and championship rival stated "I can't do that", something a teammate never says. I don't think Ricciardo would have been anywhere near as strong in 2014 if the regulations had stayed the same.
Vettel and that Red Bull were spectacular in his championship winning years, and his recovery drive in Brazil 2012 certainly stands out as one of the few times he really fought for it, instead of driving away from the front. In one lap pace, and his ability to drive away from the front he was peerless; and he utterly crushed Webber over those four years. But a truly great driver wouldn't have followed that up by being spanked by Ricciardo, rules changes or not. The truly great drivers are able to adapt and impress in whatever machinery they're given. We've seen this from Hamilton and Alonso, we've not seen it from Vettel.