It's interesting to note that one of the first points this article makes is that the term "intellectual property" spreads confusion and makes it sound like patents are something like copyrights or something like ship hull design rights.
Yes, we've heard it before and it's still silly. The term serves only to distinguish intangibles from physical objects. It does not imply that all of those intangibles are equivalent any more than "physical property" implies that boats are the same thing as staplers. This is a non-issue. It's a useful term.
It's useful in some contexts but overly broad in others. The differences between a boat and a stapler are readily apparent; the differences between a copyright and a patent, much less so. Imprecise language takes advantage of that.
Language shapes thought; people have a different opinion on the estate tax when you call it a "death tax". IP may be a useful shorthand, but it carries with it a different set of implicit assumptions than "creator's monopoly".
Well, a lot of people get very confused with this stuff, especially between design copyright vs patents. And it isn't as though Stallman is exactly original in this complaint, so it makes little sense to look on him as being the main proponent of this view. For instance, Thomas Jefferson made many remarks along similar lines.
We've heard this before from His GNUliness: