Nothing, I still use it daily at work, alongside Angular (though not together).
> how the heck did they end up settling on Angular of all things
At Google, It's convenient to use Angular because there are well-documented ways to do all of the normal things you have to do to have a production-quality front-end application, such as building reusable components, dependency injection, component testing, screenshot diffing, etc. Standardization of the framework also has the benefit of making it easier to find someone to ask for help.
It would be a truly herculean task to bring another framework up to the same level of support and integration of Angular inside Google.
Nothing, I still use it daily at work, alongside Angular (though not together).
> how the heck did they end up settling on Angular of all things
At Google, It's convenient to use Angular because there are well-documented ways to do all of the normal things you have to do to have a production-quality front-end application, such as building reusable components, dependency injection, component testing, screenshot diffing, etc. Standardization of the framework also has the benefit of making it easier to find someone to ask for help.
It would be a truly herculean task to bring another framework up to the same level of support and integration of Angular inside Google.