For the most part, everyone on the forums knows (and fears) rule #5:
5. Do not plea for sympathy- Do not make posts about how you are leaving the forums. Just leave.
- Do not make posts about how the game isn't fun for you anymore. Just stop playing.
- Do not make posts about how you are going to kill yourself. Just do it.
Most people are also aware that the penalty/punishment for breaking rule #5 is a permanent ban. However, there are some smart asses who find the need to announce to everyone how badly they're frustrated/victimized/offended by using loopholes to circumvent the rule.
Virtually everyone who tries to whore attention and circumvent a ban do so by changing their profile picture to something like this:

There is nothing subtle about Isaac Fox's profile picture. It says he's leaving and he wants you to read his signature. Even if you have no idea
what the factors leading to his departure are, you can gather pretty quickly that the reason he's leaving is because he's fed up with the community and he wants everyone to know about it.
Sure enough, it's some ambiguous message about how he's frustrated with some guy/the forums.
If you see Aphtonites, tell him to forget off. I'm sick of him and his fap material putting my reputation at risk whenever I try to make things easier for you cunts.
I'll still be playing Blockland, but I won't post on the forum. I might answer PM's.
Even better is his personal text, which reads:
Probably for a week or two. Maybe indefinitely.
I like the aura of ambiguity he's creating. "
Maybe I'll come back.
Maybe I won't. You'll never know!". Unfortunately, it's obvious that he intends to return simply because he hasn't actually committed forum Self Delete yet. If he had any intention to leave the forums permanently, he would either break a rule and get permanently banned or he'd just leave silently.
It's really obvious that people are changing their profile pictures to accomplish the same attention whoring that rule #5 was created to
prevent. In fact, it's even somewhat worse because it turns
every post they have ever written on the forums into a 'goodbye' post.
So here's my proposal: Setting your profile picture to some message about how you are 'leaving' or 'taking a break' will be considered a violation of rule #5. However because people can only read your signature if they voluntarily enter your profile, putting 'goodbye' messages in your forum signature should remain fair game.