And if you ask me, there's nothing wrong with non-commercial redistribution of publicly-available content.
Snarky response: maybe you should ask the copyright holder instead, or a legislative body in your jurisdiction, or a legal scholar.
Substantive response: how about another quote?
By making your book available online, you're giving yourself a huge publicity, and earning a lot of repute.
Substantive response cont'd: I can't decide if this is the Lake Wobegon fallacy or the In A Perfect World fallacy. Of course it's possible that Stephen King's first novel made him millions of dollars and helped him become a full-time novelist with dozens or hundreds of other books. It's easy to point to a big success like that.
Guess what? There are plenty of other novelists like me, whose first novels didn't sell very many copies at all (if they even made it to bookshelves -- so this is not complaining on my part; I achieved my artistic goals with that book long, long ago). You hear about the one-in-a-million successes and you don't hear about the nine-hundred-ninety-nine-thousand-nine-hundred-ninety-nine-in-a-million modest successes and (mostly) failures.
Put another way: it's no surprise that Cory Doctorow, editor of a site with millions of page views, popular speaker, long-time writer, long-time activist, and effective publicist can write a book, give it away online, and get a lot of attention. He's good at getting attention, especially when he does something that's very consistent with the goals and mores and ethics of the people who pay attention to what he does.
Similarly the argument that copyright infringement didn't cost J.K. Rowling substantive money fails to move me.
If my argument here fails to convince you, here's another quotefrom an earlier essay:
Perl is very hard to learn from public electronic resources alone. I believe there may even be a clash of interests because the core Perl people also write them and so may not have enough motivation to improve the online documentation. Making them public will resolve that.
Shlomi Fish, "Usability" of the Perl Online World for Newcomers
Good things happen not because magical candy-flavored unicorns fly over and drop sparkly glitter on projects where some hand-waving pundit said "All you have to do is make it a wiki and in mere seconds your teeth will be whiter, your waistline slimmer, your hair thicker, and all of your problems disappear." Good things happen because someone sat down and did the hard work to make good things happen.
Is the Perl FAQ materially better than it was ten years ago because it's easier to work on now? (I'm not sure it's even substantively different than it was ten years ago.)
There's an interesting discussion on the subject of mechanisms by which to encourage participation (and I do believe that liberal policies of contributions and licensing can encourage such participation), but the argument that merely allowing non-commercial redistribution summons those delicious sexy unicorns is hollow, shallow, and completely unsupported by facts and experience. (That's even laying aside the ridiculous conspiracy theory that suggests that Perl book authors are organized and sinister enough to plot to keep the core documentation skimpy and yet stupid enough not to realize that it's easier to get rich flipping burgers for a living than writing technical books full-time.)