One cannot look out the side window AND watch the marshaller at the same time. If you take your eye of him, you're going to get yourself into trouble.
Actually you can do this - and at times must. If you do not trust the marshaller then it is incumbent upon you to ensure that the area you are taxiing into is clear of objects.
Difficult I except, but necessary.
When turning towards the gate all crewmembers on the flight deck should ensure the gate area is clear. If in doubt stop and evaluate the situation.
In any event proceed with caution. If in any doubt stop and ask for wing walkers.
By the way my experience in Africa ops over many years has taught me to trust nobody. No disrespect intended for our African cousins as generally, whilst full of good intentions, they have never been given any training.
By the way, despite my age, I was capable of following marshalling instructions whilst simultaneously checking for objects outside the aircraft. Impossible on a 380 wing I accept. That why it was imperative to check the gate was clear before entry perhaps??
Perhaps the jetty they collided with was repositioned during their taxi in to the gate?
All will be revealed in due course.
Kind regards
Exeng