As is obvious, Hickman's entire run, even when he was handling the Avengers, is all about Reed, and to a lesser extent Doom. The Dark Reign series revolved around Reed wanting to "Solve Everything" and eventually coming to the conclusion that the only way to do so was to act independently, because other people getting involved ruins his plans/goals. This leads to the whole Council of Reeds, which eventually gets fucked up at the same time Reed realizes that his family is actually the driving force behind everything he does, and without them he his nothing. His family has to get involved to help provide the solution to his problems and right the wrongs. We also see that for all his knowledge and ability, he still lacks the driving focus and determination to pull the trigger on some things. Hence, All Hope Lies In Doom. Doom's involvement in Fantastic Four/FF was the thing needed to save Reed and his family. This teaches Reed the importance of needing other people involved, to provide various checks/balances and for those capable of doing what he could not.
Moving on to Avengers/New Avengers, it's a similar situation except now expanded with the Illuminati. The same core issue presented to Reed is now present among all the members of the Illuminati, believing that they are the only ones fit to make the decisions needed to preserve existence. But once again they lack what is needed to fix the problem, and just like before, All Hope Lies In Doom. Doom saves all of reality, but like many times before with him, he is blinded by his personal issues. It effectively becomes an inverse of what happened in Fantastic Four, where Doom needed to step in to set things right. Here Reed plays the role of" Doom, destroyer of worlds... What gods dare stand against me?" Reed has to step in to provide the needed spark, and instead of taking absolute control and acting independently (as he assumed was the answer following Dark Reign), he has learned that he needs a guiding hand so he doesn't repeat the mistakes of the past. But in contrast to the previous situations where he separated the decisions from his family (Civil War, Secret Invasion, Council of Reeds, etc), he now has his family as the primary catalyst of his endeavor.
In the end, Reed did finally solve problem #101, but as opposed to its initial presentation where its on the wall in his isolation room, he has progressed and come to the realization that solving things on his own separate from his family is not how things should be done. Fully learning to embrace his own nature while integrating it with his family has family presented him with the means to Solve Everything.