Take the diacetyl rest for example.
Without doing any research I suspect that the realization of the effect of the diacetyl rest came about through some glorious mistake.
Maybe a cellar warmed up unexpectedly, or a shipment of ice came a week too late, or the pumps leaked their ammonia. And the brewer upon sampling his/her product realized that by some amazing circumstance his/her product became, better.
Have many or all of the advances in brewing technique come about this way?