One powerful effect of Lobsters tagging is that it limits the topics which are allowed in a very deliberate way. A story should be tagged `programming` at the least, because Lobsters is about programming. This helps make it more clear when something is news, politics, advertisements, or other off-topic content that doesn't relate to what we do.

Of course, there are tags like `meta` for discussing tags. There's also a recommendation system that allows users to suggest that a story be retagged. Posting a video or PDF causes the `video` or `pdf` tags to be automatically applied. It's a rich system, not just a many-to-many listing of labels.

I like the idea of tags, but it introduces extra work in terms of monitoring for abuse, arbitrating disagreement, and depending on the tags could even introduce additional editorial bias. I'm curious how this gets worked out on other sites, especially those with as wide a variety of posts as HN.

e.g. I'm looking at the lobste.rs tags and HN would probably need a much bigger superset, or a smaller set of higher level topics