Except every ability the warden uses for power of blood is powered by using the wardens life force and blood. The Architect, or Corypheus may not have to do that because they are far more corrupted then the warden.
But I'm not say the taint is not a separate thing from blood.
Personally, I think the Warden's Keep powers have less to do with the Taint being incompatible with the Warden and more to do with Averneus' unsubtle methods of gaining access to the powers within the Taint. I would equate it to opening a locked chest with a lock picking set versus smashing it open with a sledge hammer; both give you a way to acquire what's inside, but one is far more destructive to the chest.
The Architect and Corypheus seem to be able to wield the Taint more effectively because they are simply more practiced with it. I would say the same would apply to a Darkspawn emissary using magic within the Hivemind of the horde, or an Awakened Disciple being able to cast their spells. The Darkspawn's corrupted nature may lend itself to being able to cast Taint fueled magic, but I don't think it is required.
Remember that no one had even attempted to study the Taint like Averneus did or get results as successful as he did, its quite possible that he was simply scratching the surface (or more accurately: banging on it with a hammer) of what the Taint can do.