It does seem like a fad. Kudos to those who can create a new field and profit from it. On the one hand, "chaos engineering" seem a bit like "we don't understand our architecture well enough to know what its failure modes are, so let's just poke it and see what happens," but on the other hand, it seems at least a little bit analogous to fuzzing, which is certainly a technique that yields useful results that would have otherwise been overlooked until it was too late.