When talking about failing an engine right after takeoff by cutting the mixture in say 400ft AGL, ever thought about the other engine failing because of a real problem? You would have how many operating engines than?
ZERO! Thats why e.g. Swissair Flight Academy never fully feathers a prop below 5000ft AGL. Training how to identify which engine is faulty can be done way up in the sky as well, you donīt need close proximity to the ground for that.