They have a critical mass of bad legacy code. > Because most existing C++ code at Google is not prepared to deal with exceptions, it is comparatively difficult

They have a critical mass of bad legacy code. > Because most existing C++ code at Google is not prepared to deal with exceptions, it is comparatively difficult to adopt new code that generates exceptions[....] Things would probably be different if we had to do it all over again from scratch. - https://google.github.io/styleguide/cppguide.html#Exceptions https://google.github.io/styleguide/cppguide.html#Exceptions