Allowing unlimited tags in posts has lead to irrelevant content cluttering up the site. Posts are spammed across tons of tags which makes it much harder to find relevant content in each of them (especially when browsing by "created"). Just look at the #introduceyourself tag as an example: https://steemit.com/created/introduceyourself ... ironically, this post will now appear there because I used the tag in the post.
My proposal is to limit posts to one category (still allow users to create a new one if it doesn't already exist) and do away with tags completely. This was the original method which I believe would work even better now because of the huge volume of new content being added.
This would also make it much easier to flag a post for being irrelevant because it would only appear in one place, whereas now some of the tags on a post could indeed be relevant which makes it tough to downvote otherwise good posts simply because of the tags.
Just my two steems.