I find the opposite. Being forced to consider hierarchical categorisation leads to a more powerful system in practice. It helps me create a mental reference to the item being stored. And it often causes me to see a better way to form an item in the first place — eg maybe this note is really two notes, maybe this idea can actually just be discarded, etc. Or, on rare occasions, a new item doesn’t fit anywhere (but is important) so I need to tweak the hierarchy itself — and that’s a good thing, once in a while, as it can lead to creative insights about the domain as a whole.

I’ve found tagging systems usually become a kind of dark swamp where things go never to be seen again. The lack of structure means I have little memory of what’s gone into the system, so I end up with too much duplication of ideas and inconsistency of style (mess). All this makes it uninviting and difficult to ‘explore’, so I don’t use it much except as a dumping ground, and the swampiness compounds over time.