For example, suppose AI helps us figure out a way to exploit much more of the sun's energy. Accomplishing that necessary preliminary can, on its own, take many decades, and if we split our efforts among multiple approaches, it may take longer. Intelligence can't break the actual laws of mathematics or of physics. And that's before we consider things like how resources will be allocated when AI tells people that man-made climate change and transgenderism are real.
This generation of AI hasn't even hit its first crisis. Assuming there will be none is like settlers assuming their town will never suffer a major earthquake because they haven't had one in five years.
Of course, improvements in problems that may not grow exponentially also matter a great deal, but there are too many unknowns (look at how many unknowns there are around quantum computing).