This is an absolute massive problem where I work as well.
Doubtless I suffer from it as well. I continually hear people expressing opinion as fact.
A start from which debate may ultimately be pointless if they can't see their own biases how can they accept logic.
I still think really good people can both be analysers and decision makers although I do think these people are rare - I haven't got a hard and fast theories on how duty should be separated. I can see the point though. What is the best way to structure organisations to achieve objective decision making.
I would tend to suggest - a functional organisation with an overarching management that doesn't make operational decisions but can overule functions? But then who manages the managers.
I remember reading about this some time ago I think it was debated by Socrates and was investigated by a Roman poet active in the lates 1st and early 2nd century AD who I think created the idea of Satire.
His latin phrase was - (anyone interested should lookup Juvenal)
Quis custodiet ipsos custodes?
which I am told literally means "who will guard the guardians themselves"
also referred to as "who watches the watchment?"
In those days it was the poor saying
"Who will protect us against our protectors!"
Plato's solution for this was.
We must tell the guardians a "noble lie". The noble lie will assure them that they are better than those they serve and it is therefore their responsibility to guard and protect those lesser than themselves. We will instill in them a distaste for power or privilege; they will rule because they believe it right, not because they desire it.
Interestingly this is how Hollywood plays it - for all the good guys power ways heavy on their shoulders while the baddies are meglamaniacal glory hunters.
In today's connected society though I think maybe we will guard each other reciprocally is more appropriate. Possibly a dramatic fork in the discussion.