I agree. Also, images that are meant to be included in your articles can still have long urls if you want. Unless those images are urls you want to share, of course; it's about sharing urls, and that's much easier to do when they're short.

If you've got a CMS, I suppose you could do both: store each article in its hierarchical place, but also give each article (or each article you consider important enough to share, but I would hope that's all of them) a short name through which it can easily be remembered and shared.