Debates are pointless unless terms are defined.
'Our lives had become unmanageable' is understood in different ways because people define the term 'unmanageable' in different ways.
1. Unmanageability as a corollary of powerlessness
If I cannot choose whether or not I drink and, if I drink, I cannot choose how much I will drink and therefore what I will do, I cannot manage my life. Unmanageability in this sense is the corollary of powerlessness; each implies the other.
I have been given the power to stay sober, so I am no longer subject to this form of unmanageability.
2. Unmanageability as an existential statement of the nature of human existence
Clearly, our 'lives', the array of facts, circumstances, and experiences, cannot be directed wholly by us; there are many factors that affect our lives over which we have no control.
Sometimes people deem this insight part of Step One. Maybe that was the intention, but I have never seen this spelled out in the literature as the definition of unmanageability, although the idea is indeed present in other material.
Clearly, this is a statement that applies to all people, alcoholic or not, and is not subject to alteration just because we get sober.
Unmanageability in this sense is eternal (but not actually a problem unless we fail to recognise it) and has nothing to do with alcoholism.
3. Unmanageability as the consequence of a life lived based on self-will
When I base my life around the desire for sex, money, power, prestige, comfort, thrills, and looks, (a) I am very uncomfortable emotionally (restless, irritable, discontent + page 52 bedevilments) and (b) my life is a mess practically (again, page 52 bedevilments).
This is a common definition of unmanageability. (It should be noted, however, that Fred, towards the end of Chapter 3, does not overtly fit this description so would struggle to take Step One if this were the form of unmanageability meant. He is indeed alcoholic, however, so this makes definition 1. above the most likely candidate for what the authors meant, as he does fit that description quite well.)
When I base my life around doing God's will, in return I am graced health, happiness, harmony, love, joy, peace, and connection, and my affairs become remarkably well ordered.
Do we become manageable in the sense of being relieved of restlessness, irritability, discontentment, the page 52 bedevilments, and the practical chaos of the self-centred life?
Does the Big Book promise this?
"From a trembling, despairing, nervous wreck, had emerged a man brimming over with self-reliance and contentment."
"There are two alcoholic employees, who produce as much as five normal salesmen. But why not? They have a new attitude."
"He now means a great deal to his community, and the major liabilities of thirty years of hard drinking have been repaired in four."
There are many other examples, too.
It is clear, therefore, that unmanageability, in this sense, is part of the problem, not a permanent state that must be contended with.
Controversially, perhaps, there is indeed a solution.