No, it is based on some specific design quantity or yield point - minus a (small) margin.
Regardless, if every turbine in a wind farm is going to be the same (same rating, same manufacturer, same size blades and same materials and same parts) which is the only reasonable way to buy many and build many in the same place, then you HAVE to expect them all to trip out at exactly the same point during the rising winds of a storm front. At least the power-on points are a little more gradual, since some power is produced by every turbine as they speed up, even at below-rated speeds.
If every fifth turbine were different from every fourth were different from every third turbine, then you'd have fewer chances that all would trip off at the same time (only 20% would drop off in the same wind speed), but ... You'd never keep it maintained.