Things aren't always so cut and dry. There's probably some people - a large number in fact - that does derive benefit from some of Mahalo's pages. You also have the fact that the revenue generated by Mahalo is going towards paying people which lets them live and feed themselves, etc.

In terms of the grand scheme of things, what Mahalo is doing isn't that "bad".

It's also not the ideal case either. As a savvy web user a Mahalo page is one of the last pages I'd want to visit, but I'm also savvy enough to know how to avoid it.