This is a rather common misconception about sensitivity, it is only true under the constraint where you are unable to increase the amplitude of your measurement.

Aren’t there plenty of situations where you can’t increase the amplitude of your measurement? Isn’t that why we use SQUIDS for high sensitivity magnetic measurements for example?

Quadrature squeezing is great, but I don’t think it’s the only way (or main way?) quantum sensors compete with classical sensors.