My understanding is that people who connect specifically to the NIST ensemble in Boulder (often via a direct fiber hookup rather than using the internet) are doing so because they are running a scientific experiment that relies on that specific clock. When your use case is sensitive enough, it's not directly interchangable with other clocks.

Everyone else is already connecting to load balanced services that rotate through many servers, or have set up their own load balancing / fallbacks. The mistakenly hardcoded configurations should probably be shaken loose anyways.