I think both sides are correct. Anyone with experience at the scale knows that if everyone stops working, the site becomes more reliable. Holiday freezes demonstrate this. But holiday freezes also demonstrate the other thing: if left alone for too long the systems start to rot, from memory leaks and cache ossification and other things that usually aren't noticed during active development.

Personally, I doubt that it will be anything technological that ends Twitter. It will be economic. Their advertising revenue has been decimated and their operating costs have never been higher.