Hmmmm
I agree, there are a lot of different ideas about this subject.
Where I learnt to fly, we were taught that the maximum demonstrated crosswind was a figure obtained during testing, where the pilot landed at the prescribed flight manual speeds using normal crosswind technique and directional control was still maintained.
This figure - so I was told - is not limiting as an increase in approach and touchdown speed (a common technique in a crosswind landing) will provide greater control and thus directional control may still be maintained.
As mentioned previously, connected rudder and aileron controls limit the amount of 'crossed-controls' available and will thus limit the demonstrated crosswind figure.
Additionally, the authority maintained by the rudder in combination with the friction provided by the tyres on tarmac will contribute to this figure (landing on a grass strip in a crosswind tends to be ugly on the ensuing ground roll as the aircraft decelerates).
Does anyone else find this credible, or was my instructor making things up??