So nobody knows how many patents would withstand exhaustive court challenges. Adding to the uncertainty is a change in the odds. Since patent law practices were overhauled in 1982, patent enforcement cases are easier to win and easier to uphold on appeal because they don't go to the regional federal courts of appeal. In computer software, this is not a promising trend. Rather than encouraging invention, it discourages creativity with the threat of prolonged litigation.
Patents are far tougher obstacles to competition than copyrights.
A book on the fall of the Soviet Union can be copyrighted but anyone else can write a competing book of his own. If the book could be patented, the first author would enjoy a 17-year monopoly on the underlying idea. This never happens because books are protected by copyrights, not patents. It may be that every modem maker owes Hayes royalties or damages, no matter how the competing gadget works. There's real power in patents, and real money.