Kolokotronis, I suspect the answer is the former, though one could make the argument that the "original compromises" (hmmm... maybe I should capitalize that: Original Compromises) were the means by which the heresy was able to creep in, unchecked.
I don't know the answer to this, but it is apparent that heresy is a malignancy which has been allowed to grow and spread in the Anglican Church for a very long time. As unpopular as it may be in the West, rigid orthodoxy in both praxis and belief in the Faith is absolutely necessary for the preservation of that Faith and the theosis of the People of God. Without it, everything just falls apart, the people stumble into sin, the Evil One rejoices and all creation groans.
I see the problem within Anglicanism as two-fold:
1) an unreadiness to say "thus far and no further." This is probably born of the Original Compromises, due to the temptation to say "you're already over the line." Although there has been a fair amount of back & forth over the centuries that has even led to divisions (interesting, though, that the REC is preparing a return -- and there are indeed reunifications occurring).
One solution would seem to be a statement of where the lines lie -- a rigid orthodoxy of praxis & belief, but drawn with a wider circle than the Orthodox. On the other hand, with a stronger corrective mechanism operating, perhaps "thus far and no further" could be made to work.
2) the lack of a strong corrective mechanism. I'm repeating myself for the n-teenth time here, but Anglicanism lacks the strong mechanisms for self-correction within the body that the Orthodox have. And while the Anglican mechanisms will never be as strong, they are not acting as strongly as they could -- or should. In part I blame this upon their never having been used before, thus there was a reluctance to use them when they should have first been brought to bear, and there is a continuing reluctance to use them now when they ought to be applied forcefully.
It's this reluctance that has led into what are, in my forming opinion, travesties such as "continuing impaired communion" -- "impaired communion" ought to be a temporary condition that ends within a certain time either in restored communion or no communion; it's not a measure of 15% communion, or 55% communion, or whatever. As with the condition of being pregnant, such a thing cannot be.
The hope I have, though it's not a big one at this time, is that the Global South will ultimately be successful in eliminating the big heresy and then turn to the lessers. The weapon they wield, membership in the wordwide Anglican Communion, may not seem powerful to others, but to us Anglicans who've grown up steeped in that tradition, it is significant indeed. Being outside the wwAC (as I have been for 22 years) is a little like having lost a limb.
Only time will tell.
OTOH, I've written ++Akinola before to complain. Maybe I need to make more noise.