It's less of a problem with how long patients last, instead it’s the ease and scope of patents granted.
In days of yore (and possibly still today), IBM would reach into its bag of thousands of patents, extract a handful, and allege infringement. The target might well successfully prove otherwise.
IBM would reach into its bag of thousands of patents, and extract another handful. The first defence had already cost the target several millions in litigation, not recoverable even on a finding of non-infringement.
This was explained to me in person by an individual with a long history of fighting such fights, back in the 1990s.