its like when folk tell me they can tell forks flex and maxles are stiffer.
I agree they think they can I am less convinced that they can.
with forks it's about how they track, not about whether you can feel them flex.
with cranks you can feel that more of your effort is going towards pushing you forward, rather than feeling the axle/ crank arm flex.
it's not about the individual items flexing it's about the result that higher/lower stiffness has on how the bikes feels.
I find it difficult to tune a bike's suspension because I find it hard to appreciate the subtle differences in settings, whereas stiffness is more appreciable.