Sure, but my point was there that it's really easy to use KVs as a backing store for tags, which you can implement anywhere and easily serialize. Sets, if you h

Sure, but my point was there that it's really easy to use KVs as a backing store for tags, which you can implement anywhere and easily serialize. Sets, if you have to do something like transform it to JSON, you have a choice to make: dict:true, or list.