Our knowledge bases are losing cohesion.
For instance, this + this = knowledge.
In the one, the author examines the cognitive limits of human brains, bringing up how planning is still basically in beta testing. The author examines these to try to explain why people forget or fail to carry out their plans. In the second, we find data suggesting that willpower isn't just some metaphor, but an actual physical thing that can be depleted.
If these two people, (plus their teams?) had ever gotten together, they'd both be much richer. Yet, not only are they observably independent, there exists no mechanism to bring them together. There are no 'meta-scientists,' devoted to synthesizing the related findings of disparate fields, and there is certainly no one channeling the thoughts of these related thinkers to each other.
Even if someone were to implement a society of meta-scientists, dedicated to essentially being a proactive human-implemented Google, eventually the learning limits of the thinkers would be reached, and it would be physically impossible to socially empower them further.
In tribal humans, once they reach the Dunbar Number, it has been calculated that 42% of their time would be spent just socializing. We can see this as the maximum amount of time to be able to socialize and still do something useful. Analogously, once a modern human reaches some time-percentage of being taught, it is useless to attempt to teach them more.
Further, this feeds into the idea that social structures have carrying capacity, measured in complexity and size, similar to ecological carrying capacities. The simplest explanation for the fall of Rome was simply that they tried to get too big. The sub-reason for this was that their particular structure required growth, otherwise they might have realized that it was time to stop growing.
This idea is the inverse of the related idea that greater social technology is needed to create an agrarian society over a hunter-gatherer society.
If this idea holds merit, we can clearly see that American society is groaning under its own weight. Democratic government always expands, for the simple reason that contractive ideologies do not win followers. (See Mencius Moldbug.) The market has been expanding as well, so the demotic expansion has so far been supported, but eventually the market must reach our social carrying capacity. Once it does, demotic expansion will almost instantly catch up and overtake the supporting market, squeezing it out of existence, and our society will collapse.
As with the examples above, cracks are already appearing in our social structures, indicating a loss of cohesion as a result of expansionary pressure. I will not say more; doomsayers, both mainstream and internet crank, are already abundant enough. It's fruitless to add more, as the task of sifting true doomsaying from false is basically overwhelming.