There are useful patents though they may hinder more then they help depending on your PoV. Various codecs and some crypto algorithms come to mind.
You run into a lot more useful ones at the intersection with the physical world where some protection lets a company get a chance to be the first one to market and reap some benefit.
In some industries (Pharma) it's really the only practical approach due to the extreme development costs (easily over 1B$) and often cheap production costs.
To be clear, when I say "patent" I'm referring to a legal instrument that secures exclusive rights. When I say "useful patent" I'm talking about the utility of the legal instrument, not the utility of the mathematical algorithm claimed in the patent.
You run into a lot more useful ones at the intersection with the physical world where some protection lets a company get a chance to be the first one to market and reap some benefit.
In some industries (Pharma) it's really the only practical approach due to the extreme development costs (easily over 1B$) and often cheap production costs.