With "flash protection" you mean the ability to break the short circuit level at the location, right ?Fuses are needed for flash protection, don't ever rely on a CB. Period.
The CB you mention simply wasnt rated to the short circuit level that it experienced. Thats a fault of the designer of the electrical installation.
Fuses also have a rated short circuit level. To use fuses doesnt universally guarantee that the short circuit current can be interrupted.
In all cases every design must be checked that the short circuit level at the location doesnt exceed the rated levels of the devices intended to provide protection.
Period.