I don't know why you keep bringing up the Brendan Bell comparisons...
Bell was a 3rd rounder, not a 5th overall pick. When Bell won the CHL defenseman of the year, he was in his overaged year, turning 20, 2 years after being drafted. Rielly is 18 turning 19, a full year younger right now. Bell did not have any of the elite attributes that Rielly has coming out of junior, or else he would have been a 1st rounder.
If you're using Benden Bell to discredit Rielly, then you may as well use Brenden Kichton to discredit Seth Jones. Kichton currently leads all WHL defensemen in points, ahead of Jones, after being a 5th rounder in 2011. Let's ignore the age gap and all other factors that influence points for a defenseman and say Seth Jones is overrated since he can't even out-produce Brenden Kichton.