Because it helps the comprehension of all the machines, belonging to giant corporations or otherwise. And if they understand the site, they can use that informa

Because it helps the comprehension of all the machines, belonging to giant corporations or otherwise. And if they understand the site, they can use that information to help us, the users, by presenting relevant search results about caramelising onions and the semantic web and so forth. Yes, it will help Google sell advertising, but the benefits to the rest of us far outweigh that minor inconvenience to some people's idealism and politics.