From following the comments, everyone seems to have thought this through a lot. It shows the diversity of we who love the game and helps me understand a bit more why the games' creators have problems in bringing back the Warden - or at least a Warden. With this latest installment of Dragon Age I think it is obvious that the Inquisitor holds the power not only to stop the mages who unleashed the blights but the blights themselves.
I appreciate all of the comments pro and con. I just finished Adamant again and seriously considered my stance on the Wardens. Their stance has always been that what they do is for the greater good. Perhaps some of you are familiar with Karl Popper's work where he points out that if the greater good is defined as the greater happiness and someone who believes this has a weapon that would instantly and painlessly eliminate all life, they should use it. After all, without all the misery from famine, poverty, illness etc. the concept of greater good would be served. Of course it would not be for the world's good, nor for the good of the people, but it would serve the greater good.
From what Bioware itself has told us, the Wardens believe the ends justify the means. If you refuse to drink they murder you. They are easily corruptible by blight tainted creatures of intelligence. They have willingly touched off the war in DAI resulting in the deaths of thousands. So when I got to the point of cleaning out Adamant I booted the Wardens again and let Stroud stay in the Fade. Apologies to those of you who disagree. I respect your opinions but I cannot get past the secret murder / do as you damn well please attitude nor their weaknesses. Solas comments that they do the fighting the Blight poorly, a topic I wish I could have questioned him on. So, I make no leaps of faith here. From Bioware's own text I have no faith in the Wardens as a group. As individuals, of course, I judge them as such.