[jljljl]

At the scale of a company like Twitter, the product and infrastructure are less like a static bridge and more like a complex living, evolving organism. So the analogy is not a very good one.

So your patient might be ok if you fire Ned, but if you try to make changes and a critical system goes down, it might take you a lot longer to fix things without the specialists in that system.

You could keep one specialist around for each system, but then you have a very small bus factor.