Yes it is down to pilot skill and judgement and no it would not invalidate your insurance if you prang it during a landing with a 17kts X-wind.
It is not a lmitation.
IF my memory serves me well manufacturers only have to demonstrate that their mount is able to be landed with a crosswind component of at least 0.3Vs.
Nowt more nowt less.
That is why some STOL aeroplanes have a ridiculously low demonstrated crosswind, their stall speed is low so 0.3 * is going to be very low.
Maule = 12 mph.
They easily handle a lot more.