I certainly see the resemblance, but I don't think that webpage keywords and tagging systems are exactly the same. One major difference is the identity of the

I certainly see the resemblance, but I don't think that webpage keywords and tagging systems are exactly the same. One major difference is the identity of the tagger. The creator of the page is generally the one adding the keywords, so there is an inherent bias that is different from the perspective of users who add tags (though they're biased in their own ways). Ideally the perspective of the tagging users align with the perspective of users who are using the tags to access content, and so the users following the tags end up reaching content thats most appropriate.