If you're looking for a good reason why that wouldn't work I think you might want to look at the rise and fall of DMOZ which is known as The Open Directory Proj

If you're looking for a good reason why that wouldn't work I think you might want to look at the rise and fall of DMOZ which is known as The Open Directory Project. The problem with such an idea (which could be solved but is challenging) is that the web evolves quickly, and it takes funding to keep up with that. It also takes people to do that work, and while you can crowdsource some things with ease I think hardcore search engine really takes some specialization. That said it's amazing to me how much of the web and internet is open. If you think about it something like Wikipedia is very useful and not owned by a corporation. If if you think about it that's sort of amazing when you look at the history of technology.