Obviously redundancy is better. But some allowance can be made for pilot skill to work around a problem. For example, a loss of airspeed at cruise should not

Obviously redundancy is better. But some allowance can be made for pilot skill to work around a problem. For example, a loss of airspeed at cruise should not cause a disaster. The pilot can select a know good thrust/pitch setting and use other data (such as engine performance). There will always be this kind of failure that needs a workaround rather than complete redundancy. The risk is possibly in how pilots interpret and respond to that information.