>Your tone also implies that large, complex systems, even if designed well, don't normally require a lot of maintenance from many people.
That's correct.
In the case of Twitter, it was disclosed that many of their systems were running out of date EOL software, to the point of being a security liability, which raises the question: if the systems weren't being maintained, wtf were all those people doing? Taste-testing the free food and cappuccinos?