Small developers aren't immune to such activity. To the extent they do business with large companies, they can always be dragged in as co-defendants. "Apple: Samsung stole our technology and gave it to LittleCo, who were are suing separately for tortious interference with a contract."

The point is that if there really are so many entities just trying to abuse the system, they don't need patents to do it.

Small developers are best protected by patents, which simplifies using the judicial system to enforce their rights. Otherwise they would have to use a more messy system of contracts, as rayiner describes.