What I don't get is why you like doing it.
As I say, all it does is make a post that little bit more effort-expensive.
It's obviously not going to kill me and I can easily just delete it from a quote when I quote the post (as exampled above) but it's just one of those little things that costs nothing and makes miniscule improvement, so I can't understand why anyone would do it.
As for other forums, CW enjoys a higher calibre of discussion than elsewhere and thus differences from other forums are to be expected and not remotely surprising.
The whole point of signatures is to do what you do manually every post.