ios8 leave group chat/conversation

I was very excited to hear about this feature in ios8. Unfortunately it doesn't seem to work. Most of my group text conversations don't have the option to "Leave Conversation". I read somewhere that there needs to be at least 4 people involved in the conversation to have this option, is this true? And if so, why? That seems a very useless requirement. I've been stuck in a 3 person conversation for over a month now! I tried the "Do Not Disturb" option, but this seems to be broken as well. I still get notifications popping up at the top of my screen whenever someone sends a message in that convo. This is very disappointing. Hoping this gets fixed in a future patch.

Also, while I'm here, I might as well say this too: I tried to post this question twice from my iPhone 6, but for whatever reason this page (where you fill out the form to submit a question) is broken. None of the text that you write shows up on the screen. And you cannot "Post" the question.