GD, I work over the cube wall from our warranty department (OEM manufacturer). I write recalls, interact with our legal counsel as well as with NHTSA reps.
"Sudden loss of control" is only one of the criteria used by NHTSA to determine if something needs to happen. A cat disintegrating, locking up the turbo or taking out the engine is absolutely something that could be covered under a safety recall because guess what, if you engine munches your turbo, you lose the ability to accelerate, brake with power assistance, steer with power assistance, all things NHTSA generally frowns upon. Is it likely to happen? Maybe not, but it could, and that's all that matters really.
NHTSA isn't only interested in safety, that's why they have a customer portal on their website, the link says "Report A Problem," and there is no criteria given for what they consider acceptable types of complaints.
Manufacturers generally don't initiate recalls on their own, unless people are dying or the company stands to lose millions in dissatisfied fleet buyers, so it's really on us as consumers to report anything and everything. You may disagree, but take it from someone working in the belly of the beast...