They're mechanical devices, of course they can fail. There isn't an engine brand/model out that has never had a failure.Do you disagree with the following?
Engines can fail unrelated to OCI. Manufacturers can deny warranty for violations of their warranty conditions.
I doubt the legitimacy of the claim, or, there is more to the story. The failure was not caused by the oil or the periodicity. If this is true, then shame on Mazda for trying to explain that as the cause. I do not see where Mazda explained the exact failure?
I 100% maintain, assuming true, that this is a waaaaaaaaaaay outlier. Probably every manufacturer has a horry story. Every one.
Also, Mazda isn't wrong about requirements to maintain warranty, but I seriously doubt the oil as being the cause here and CERTAINLY NOT systemic to the Skyactive 2.5L.