Ab, PM, rather than being overstated perhaps the icing hazard and others quoted are under-reported or poorly understood, particularly on a worldwide basis.
I recall that risk involves both frequency of occurrence and severity of outcome. Thus very few crews may have encountered severe icing – a rare event, but when encountered the effects can be major and develop rapidly.
Crews may not understand the relationship/disparity between the various definitions and thus reporting is inaccurate; also there have been reports of a widespread belief that all aircraft can cope with (any) icing which of course if far from fact.
If ice is forming on a heated windscreen, even at the edges, who knows how quickly this might spread all over the screen. Compare this with a car windscreen when entering a patch of freezing fog.