[note: I wrote the Warcraft article]
/agree
If the patent-standards for the 80's and 90's were as awful as today, I'm sure that some CAD company would have locked up the idea of drag-select, and the Macintosh WIMP interface (and hence MacDraw/MacDraft) would have been legally impossible to create.
On a related note, after Blizzard Entertainment was acquired along with Sierra Entertainment in a corporate merger, I got to meet one of the principal developers of some of the old Sierra-style adventure games. One of his first questions was about the Warcraft path-finding algorithm. When I explained how I had written the algorithm (which I invented independently -- never having done any reading on path-finding), he said (more or less) "yeah, Sierra has a patent on that, but we don't enforce it". Incidentally, the algorithm was awful but functional -- it's apparently known as "crash and turn", but was clever in using minimal CPU since it had to run on the limited computers of the day.
The fact that it was possible for Sierra to patent something that a junior programmer like myself (at that time, 3 years of professional experience) could invent from whole cloth shows how weak the patent system is for software engineering.