First of all thanks for trying to provide an explanation.
I'm certainly not searching for other games that have multiple threads open asking you to close them or ask for an explanation why thread ... wasn't closed as well.
This thread has 452 pages by now. So let me just quote a part of the OP of the closed thread.
I think it served a purpose and wasn't just a double and making things more complicated and confusing. But that's just my opinion.
Yes, I read the OP. Not saying it didn't serve a purpose, but with the exception of fan art, what you outlined as the topics of the secondary thread are what is discussed in every other game thread on the forum - including those with a thousand pages or more.
The current structure of the forum is such that if you find the game thread, you can get all the info you need about that specific game. If we allowed a separate thread for future content of your game, it would set a precedent and we'd have to let everyone do it, and not just game devs since for many games the dev isn't active on the forum. I'd hope you can see how that could quickly get out of hand; "bas' Holiday Island game tips thread", "klx's Holiday Island FAQ", or "no, there's a new bug report thread after update v0.4c, you're using the old thread". Not kidding even a little, I've seen forums like this.
Every thread has people who refuse to use the search, asking the same questions that have already been answered over and over. Every thread has people asking when the next update is when it's literally the post above theirs, and asking for saves, walk-throughs, and the Android version. If we had a good solution to manage this, we'd implement it. And no, mass banning isn't an option, appealing as it sometimes is...
TL;DR - we can't do it because it would create bigger problems than those it solves. Sorry.