I ave seen more than a few Glocks that "just stopped working." Quite a few, actually...
I've seen a few Gen 3 G22s start choking when WMLs were attached, but that's it. None that just quit. Not doubting your experience though.
I've seen several that had broken pins that were only discovered because of an annual inspection. They were still firing just fine. Granted they shouldn't have sheared in the first place, but still.