>>But the key point is that it's used briefly and specifically to draw attention to an individual item.
Microsoft also causes a dialog to flash if you try to move focus back to the underlying app without closing the dialog. Flashing is acceptable as a cue for "you are here" rather than an attention-seeking device for a field or value.
I have no issue with medical apps flashing problematic readings either. Check out "the machine that goes ping" and the visual and aural cacophony it creates if it doesn't like a reading. Those machines cost a lot more than a PC and are designed to the nth degree to satisfy caregivers and avoid litigation, so IMHO their GUI decisions are just as relevant as those designed for office workers.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1