@Flexibile:
Do you think it fair to presume that the pilot in this aircraft didn't have an instrument scan going? (Called by some a 'crosscheck')
If you are on instruments, then you fly with the AI/AHRS/HSI as your primary reference. You get trained to do that when you get an instrument rating.
(Granted, any of us can have a scan breakdown on a bad day).
So while what you say has been shown to be true, the remedy for that issue is also known:
establish a scan and use it to maintain attitude, performance, etc.