Despite Webber's horrendous record of incredibly bad starts, Vettel is clearly superior to him in the same car. Vettel is likely the best driver in F1 at the moment. I doubt many others, if anybody, could have pulled off what he has in the last two races. He is simply brilliant during qualifying and the first few laps where he typically gains a sufficient lead so P2 can't use the DRS to attack him.
Is the Adrian Newey designed Red Bull car superior to all the rest? There is little doubt of that, but the differences are not all that great as they were in the past. Both McLaren and Ferrari responded quite well to make their cars more competitive during the year.
Winning championships in F1 take 3 major elements: The car, the driver, and the team to properly prepare it and respond to pit stops. Without any of them, it is quite likely that one of the other top teams will win instead. Any of the drivers for the top 3 teams are capable of winning the championship given the right car, the right team, and the right amount of luck. But the top 3 drivers at the moment are clearly Vettel, Alonso, and Hamilton. Any of them would have likely won if they were driving the Red Bull this year.
Four years ago, the Brawn car was clearly superior to all the rest at the beginning of the season due to the rear diffuser. Button was essentially handed easy victories at the start of the season which made his lead insurmoutable. That was really more of a technical fluke than anything else. The FIA really screwed the pooch by not disallowing the double diffuser design which would have leveled the playing field and made the season far more interesting.