"Hardware limitations" are extremely unlikely in my view to establish useful limits.

Consider: Do hardware limitations establish useful limits on the kind of problems a computer can solve? The answer is a resounding NO in my view, because the limits of what can be expressed/solved grows so insanely quickly that it becomes a completely meaningless and unreachable limit even for super small computers (less capable than our brain).

As for learning time constraints: These are obviously reachable, but still useless in my view because they are too inconsistent- the kind of methods and insights that a human can acquire within a lifetime are completely different between persons, and highly dependent on how the learning happens...