In the abstract, it's sort of like asking "How can there still be traffic jams on road XYZ, when there's an open lane that was added recently?" The problem isn'

In the abstract, it's sort of like asking "How can there still be traffic jams on road XYZ, when there's an open lane that was added recently?" The problem isn't the number of lanes, it's that fundamentally that mode of traffic (mass individiual transit) has capacity limitations, which when exceeded cause it to go into a "bad" state, after which recovery is difficult and arduous. Furthermore, just because you stop letting cars on the specific road doesn't mean the jam resolves instantly; you actually have to significantly reduce pressure over time before that can happen. And that jam causes cars to overflow into other roads, causing other problems. Just removing the "trigger" (too many oncoming cars) that caused the problem is not enough to recover from either the initial problems, or the side effects. People here are using all kinds of networking/hardware analogies and while generally I'm loathe to use those (they often reek of "All I have is a hammer"-syndrome), you do see these problems a lot in such designs. A good example is when something like a database goes down due to having too much load. Recovering from this failure often isn't just a matter of going from "too much load" to "enough load to handle", you actually have to shed significantly more load than that to recover the system, because that initial failure might cause a cascade of failures that prevents that. This often manifests as a kind of ritual where a system admin pulls a big number of levers in the engine room all labeled "Do Not Touch" in just the right order to shed load and reboot things correctly. Real world supply chains are doing the same thing, but their actions are priced in and done months in advance. Logistics is a hell of a thing. I realize this is not a concrete answer about electronic supply chains (someone else can handle that) but rather a more abstract classification, but I think the general idea applies here.