Exactly. The likes of Microsoft and Oracle have diverse software while patenting every improvement that they can. For instance, Microsoft has patents on cut and paste, Oracle probably has patents on key database/ERP tech, and Apple had patents on common smartphone idioms. Patents on popular, must-have features give considerable leverage against a company that has little to bring to the table. Google wasn't about to give up PageRank, their cash cow. They'd rather risk a long lawsuit and financial loss.

Anyone that thinks patents aren't leverage can try to force IBM out of their market or take most of their money with lawsuits. Just like IBM themselves have successfully done directly or with indirect threats of it supporting acquisitions. Just try. Spoiler: it's not going to work and their countersuits might be interesting.