But in that type of failure, you can't control where the pieces go.
https://abc7ny.com/philadelphia-emergency-landing-southwest-...
It resulted in depressurization and partial ejection/death.
"Two small punctures were found in the right side fuselage just below the window belt with material transfer consistent with impact from pieces of an engine fan blade"
(From the link in parent to this thread https://avherald.com/h?article=4b4e8ca7&opt=0)
However, loss of the shroud doesn't necessarily imply there was a confinement failure. Damage to the shroud during the event can easily lead to the cowling shedding aerodynamically, which is also part of the design: the last thing you need is more drag on the dead engine side. We can't tell which that was in this case, but it's important that we do---the design criteria specifying that the aircraft can be safely recovered from a catastrophic single engine failure during any stage of flight would assume the failure is confined to the engine.