Regarding the IC dogma, my personal opinion is that it came about as a bug fix.
The prevailing concept of Original Sin in the west is fundamentally flawed. There is a sense of total depravity in humanity. A symptom of this is all the agnst over justification, which divides Christians today.
The traditional early high regard for the Holy Theotokos cannot be sustained in an environment like this unless she is made an exception and not born like the rest of us. So the IC dogma was declared as a kind of ‘patch’, a ‘bug fix’ to western theological programming to preserve both the western notion of deparavity and the older traditional notion of the Holy Theotokos’ purity.
So that’s what we have now. Westerners arguing over whether she is as depraved as the rest of us from birth, or whether she is not.
This explains why Eastern Christians often have a hard time answering the question of whether they believe in the IC. Maybe yes, maybe no.
It depends on what one thinks about original sin. Roman Catholics often try to claim that they believe the same things about original sin that the Orthodox do, but their need to preserve the Holy Theotokos from original sin clearly shows that they do not see it the same way, regardless of how they describe it.