The wikipedia article doesn't explain it well compared to the accident reports.
The regulators were trying to test the envelope protection system under stressful conditions and it turned out that the AoA vanes were non-functioning which contributed to the crash.
Thus it is relevant to the later 737 MAX crashes.
It is a "normal accident" because of the human factors: e.g. no flight plan filed because it was a test flight, regulators ordering the pilots to defy the air traffic controllers, regulators ordering pilots to go forward with a test they didn't want to do... And on top of it all a maintenance error.
The regulators were trying to test the envelope protection system under stressful conditions and it turned out that the AoA vanes were non-functioning which contributed to the crash.
Thus it is relevant to the later 737 MAX crashes.
It is a "normal accident" because of the human factors: e.g. no flight plan filed because it was a test flight, regulators ordering the pilots to defy the air traffic controllers, regulators ordering pilots to go forward with a test they didn't want to do... And on top of it all a maintenance error.