What I wanted to mean is that if you use bookmarks as a reading list, you are better off not using them for any other purpose, like saving articles by categories for later reference.
This is because each bookmark can only be in a single bookmark folder.
Additionally, if you have an addon that makes bookmarks, and it creates a bookmark for a site you have already bookmarked (let alone mass creates such bookmarks), the old ones will be lost along with their tags.