the difference between missing and confusing indications
From various posts I get the impression that the difference between missing indications and wrong indications is not always fully recognized.
Flying partial panel is easy if some instruments are just shielded off. It's a different story if they show conflicting information (e.g. a toppled horizon). It gets really difficult when not only airspeed shows impossible values, but other airpressure derived readings like altitude and climb/descent rate go to their stops (which they might do if static ports are clogged). Combine this with the sudden transition of a quiet lazy night flight into a nightmare of flashing alarms and horns, tripping autopilot, autothrottle, runaway trim system, law changes and a thick black night in IMC and the old man not available. The crew did not have the option of pressing the "pause" button and sort out quietly which readings make sense and which do not and consider what the hell had hit them. A stream of computer messages just added to the confusion.
It would probably have been much easier to fly this "no pitot" aircraft with a dark panel, using the standby horizon only and the throttles. But alas the displays must have shown a nightmare of utterly confusing and jumping readings, flashing symbols and a cacophony of warnings and alarms. Too much for the poor crew. Manageable maybe for some well trained and fully alert crew but certainly not manageable for most of the pilot bashers contributing to this forum.