Competition is the core of capitalism. Competition between companies lowers prices — on average — and ensures that they are forced to innovate lest they lose their markets to others. Competition between workers ensures that people strive to do their best work lest their jobs go to more qualified or faster or cheaper replacements.
Obviously, there is a spectrum here from lethargic monopoly to cutthroat competition that causes more problems than it’s worth (environmental damage in the hopes of cutting costs, fraud, deceit, etc.). Drawing that line though is really, really hard though, and there are unfortunately not many non-academic discussions of how much competition is needed to spur innovation.