Network software has made it possible to keep trade secrets perfectly. When you deployed something physical, people could analyse it in detail, trying to figure out what the ingredients to your drink were, pulling apart your widget and measuring it very precisely, that kind of thing. Some would be easy, some would be hard, but it was all at least physically theoretically possible. So the patent system said “save us the trouble of figuring it out, and we’ll grant you a monopoly on this particular approach for a while”.

But with network software, the interesting part is out of reach, so you can’t reverse-engineer it.