Just how was it that technological advancement escaped them? Why did Gregor Mendel, the father of modern biology, live as an Augustinian priest and not an Iroquois? What follows is supposition based on some small research. I'm open to correction in the comments.
First off, the Iroquois were essentially communists. That's not a perjorative statement at all. In fact, their communal support of each other was the envy of the European settlers during times of famine. The Iroquois shared what they had much better than the settlers. However, being collective in nature, they expected each person to fill their role. Men did all things related to the forest and women did all things related to the field and family. Mendel would never have gotten off the ground.
Gregor Mendel fiddling around with his pea plants would have been pressured to get out there and hunt with the rest. His work was independent and unusual. It required a society that valued individuality and could not have been done in a collective environment. Mendel had an infrastructure around him in the form of the Catholic church that gave him the freedom to research and study and valued his acquisition of knowledge. By the same token, that infrastructure was willing to support the alchemists of the time who were looking to transmute lead into gold. Research, being by it's very nature filled with the risk of failure, would not have been suffered by the Iroquois.
There are other, obvious reasons for Mendel not being an Iroquois. The lack of a written language makes scientific research impossible. That lack of a written language comes from a lack of a need for one. I would suggest that comes from their societal structure. If the guys all get together in the morning and go out to whack deer and the women all head for the fields with their kids in tow, what do you need with writing? As far as I recall, math and writing came from commerce. What need is there for commerce when everyone is working together on the same projects?
I suppose the Iroquois could have developed Gantt charts to track their progress, but even the Iroquois knew enough to avoid Microsoft Project. The next thing you know, they would have all been going to Lean Six Sigma training. I think we're all glad that didn't happen. We would have missed out on all the good things the Iroquois accomplished.