@Adisfatm I think it's more of a recommendation, because declutters the post and makes it easier to read (I think that's the reasoning). If you really need someone to get a notification, ping them. Or just wait a few seconds before posting, it's easier for everyone. Doing it once in a while isn't too much of a problem, but if you do it too much, the mods are going to talk to you about it
Edit: Swat said it better on this thread