In some ways, patents losely correlate with R&D spend. So when a new play enters a mature field, they'll lack patents and end up having to license patents from

In some ways, patents losely correlate with R&D spend. So when a new play enters a mature field, they'll lack patents and end up having to license patents from companies that did the hard R&D. It's a way of allowing R&D externalities to be captured. The system doesn't work all that well, but that is the intent.