Because now we have "Ignore Topics", you never know if someone will see your post or not. If we had a CAM topic which couldn't be ignored, then if you wanted to get hold of someone for some specific advice, you could post there and know that they would see it.
For example, if I want to get hold of Marslady, I need to guess which topics she will see, and post in one of those. But she might have completely gone off Chat! and never see it.
I know people will say "that's what CAT is for" but not everyone has CAT and not everyone accepts them.