Right... I replace my fork before I replace my cassette...
Carbon either fails or it doesn't. The forks in question were structurally too weak to deal with all the load conditions; i.e. some load conditions were overlooked during the design of the fork. A rider riding the fork will be fine until they happen upon one of those load conditions. In this case, it appears that the load condition in question is a front impact crash condition. If you have a carbon fork and crash it headlong into something (or highside it as this can produce similar loads on the steerer), you are probably best to take the fork off the bike and look it over very carefully before riding it again.
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Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --
the tiniest sprinter