Redundancy is good when it's understood and when the protocols to keep everything running are understood. I heard about an Airbus with 9 computer systems (ELACs x2, SECs x3, FACs x2, and SFCCs x2). When each system began to fail, the plane behaved more or less normally, so the instructor on board reset the computers and kept going each time. Each of those systems eventually failed, and the plane went to it's mechanical backup system as a last resort. Unknown to the entire crew at that point, that meant that the sidestick was effectively a piece of functionless plastic and the plane could only be controlled via rudders and pitch wheels. I watched the video earlier today, it was made by Mentour Pilot. Dude's fantastic at highlighting exactly what went wrong and why it's not necessarily anybody's fault.
