All I can think from the benefit of 17,000 hours is......use arm rests if you want to, and don't use them if you don't want to. It makes no difference! As for the strong crosswind case, probably best not to use them, but try out full and free movement of the controls on the ground to be sure you are unimpeded. but don't let removing the arm rests before a windy crosswind landing put you in a mind frame of making over large control inputs!
A big problem in aviation, as well as in many other areas, is people making up rules to suit themselves or their opinions as they go along- and expecting you to conform. Sort of 'shoot from the hip' rule making, and try and pretend 'it's official'. Sometimes it's easier just to go along with it and nod your head politely! Or if you strongly disagree, you must ask to see it in the manual.