In amateur boxing (olympic & certainly in the UK) headguards have been banned because fighters are likely to take more blows to the head if they're wearing a he

In amateur boxing (olympic & certainly in the UK) headguards have been banned because fighters are likely to take more blows to the head if they're wearing a headguard, causing more trauma and more eventual damage to the brain - not sure the analogy holds up for cycles or motorcycles though. Interestingly, bare handed boxing often results in far less head trauma - and while it tends to result in more cuts it has far less of an effect on fighters long term health.