I suspect that this is because if an article is approved, you want that to be reflected in the object right away. However, that behavior may not be desirable for other properties such as ViewCount or AverageRating.
For example, let's say an article has been viewed 57 times. When a user pulls it up, the ViewCount will be incremented to 58 in the database, however, the page will still show 57. In other words, it is showing what the ViewCount was before
the current user viewed it, which is probably the behavior the author intended.
Whether or not you agree
with this behavior is a matter of preference. Either way is valid.
By the way, I wouldn't sweat the instance properties in the BLL too much, as most of them are never actually used anyway.