Earlier quoted context omitted.
That's really a great point but Joel's board is not exactly the same as Craig's list. Joel's point was that Craig removed the revenue from classified ads, when the money was being used for the public good. He acknowledged that the classified ads market was fair game, but he disagrees with Craig's view that he's doing the most good keeping it free. I think there's a notable difference to Craig's list being free vs Joe…
And there always will be a place to go for free ads, now that it's been noticed as a good idea for a website; whether it's Craig's implementation that survives or not makes no difference. The cat's out of the bag: classifieds can be free.
In general, the free things that are good still require some sort of commitment. Money is just one of the most fungible sorts of commitment.