William Herrin wrote:
It wasn't forgotten. Folks gained a lot of experience with anycast DNS between 2002 and 2006. Not withdrawing the routes when the servers are deemed malfunctioning turned out not to be an operationally sound practice. The theory offered in 3258 was wrong.
So, from limited experience, you thought it were wrong because:
Simply turning themselves off, instead of withdrawing the routes, would result in suboptimal performance.
But, this time, the reality strikes back. That you can be safe 99 times out of 100 can mean remaining 1 time is totally disastrous. When servers are deemed malfunctioning, the best practice is to check whether the servers are really malfunctioning or not before blindly shutdown the servers. Masataka Ohta