Centigrade is calibrated using pure water, which is quite difficult to produce. Fahrenheit was calibrated using things that were easier to find. The Fahrenheit scale came first and was successful because it was easy for people to calibrate thermometers to use it. Most of the world (i.e. pretty much everyone except the USA) switched to it decades ago because distilled water is now quite easy to produce (and thermometers are not manually calibrated anymore, they are mass produced within tolerances that will give a certain calibration and so the issue of calibration difficulty is not applicable).