Liza, and the rest of the team made the forums so everyone could see and help (Technically discourse made the forums ). Quote again from her:
People may feel left out if you hide the topic from them, but they know it exists. Think back to the time when you weren't a regular (or aren't a Regular), and someone made a topic in the lounge. Weren't you slightly upset, or even jealous? People might feel the same and we don't want unhappy Hopscotchers! Most people don't even read everything or anything, since most of it is chatting about ideas.
The Hopscotching community is extremely large and the forums users only take up a small percentage of that. It's still basically a surprise! Hiding collabs might not be a good idea. I've seen many people join collabs, who weren't originally invited, because of their great ideas. You wouldn't want to regret keeping a great idea from your projects would you? Also, it's not the best idea to create a surprise for one person, as it is not fair to the rest of the people.
We're not afraid of people being mean to each other on the chat, but for others who feel badly about themselves not making it to the collab. To feel declined is a very unhappy feeling, and people will go to great measures to break it, to be in the collab. You don't want a group of haters chasing you, posting mean comments, everywhere you go just because you rejected them from the collab.
Opening and closing topics might not be good as anyone could close and open any topic any time. Leaders and admins can because they are trusted. Now, there are many good people who know what to open/close, but there are many more who abuse the ability.