I may not be the best person to answer as I would only call myself moderately economically libertarian. Obviously to anyone who knows the history of oil exploration, Standard Oil was good during it's growth phase because it out-competed many who were less efficient and much more damaging to the environment. Once they had essentially cornered the market that generally reduces/ eliminates the need to further innovate to out-compete non existent market players and competitively price their product.

My understanding is that retrospective analysis showed that they were not abusing their monopoly towards the consumer (their competitors were another matter) and the break up resulted in Rockefeller temporarily becoming even richer. I'm sure that there were eventual benefits to the competition between these companies since primary resource exploration & refinement is not a natural monopoly.