I’m not sure I share your view.
Well in that case we shall discuss. That was my intent for this thread. 
I find interesting and important information in very old threads quite frequently. Some can be outdated and even misleading, definitely, but there’s very useful discussion there as well.
Yes, I agree. Some old threads are great to understanding the vision for a certain feature or why something exist. They should be preserved. But some threads are just useless bloat. There are some thread which raised an issues years ago and is dormant and never invoked curiosity. These kind of threads can go.
Let me be clear, I am only referring to threads that have no value addition. Whether the thread is old or new, doesnt matter.
For example, the thread that I meantioned in my opening post, is absolutely invalid today. It was raised in 2014, and is about job work. I wanted to post a question on job work, though its the very close to what i wanted to ask, I still dont see the point of bumping up this thread. Its better to start a-fresh. Its 11 years to the thread with no response and things have evolved since then and this thread deserves to be deleted.
I wasted 5 mins reading the thread, and I dont think someone else should spend their time on it as well. And there are a ton of these out there. But I have no way to delete it or it bring it to someones notice that it needs to be deleted.
That is why manual intervention is required. To decide what needs to go. I belive that the current discuss forum has evolve much further and needs to have a reputation of having good answers. Just like StackOverflow. Its ethics to not allow vague/incomplete and vetted questions result in a quality QnA forum.
Additionally I think a lot of questions by new joinees, never get asked because they may think that it wont get answered.
But worse things happen today, with people posting questions on telegram group, which gets drowned after 5 mins. (unrelated pun, but discussion for another day)
I believe that users will come to forum more often, when its more cleaner. I would say that a user will prefer a forum with 20 geniune top class QnA, rather than a 1000 crappy ones and a few good ones.
The forum has experimented with auto-closing threads a few times I believe, but it’s hard to set a fixed rule for when to do it.
Yes, so I would go against auto closing. Because auto closing cannot be done on the basis of dates. But on the Content. Automation is not the answer to this problem.
Thats why, I strongly recommend a group of administrators for the forum, who will vet each and every new question, and vet every thread that was raised in the past, and decide what to keep and what not.
Often it makes sense to start a new thread rather than raising an old one from the dead, but sometimes adding to an old discussion is better.
Agree, and this is the decision that the administrators have to conclude, as to is the thread good enough to keep or to discard. But we cant leave the all the questions open, just because a few of them could be of value. We only keep the questions that matter.
The administrators have to be the ones who understand the product completely and decide on the fate of the thread.
Obviously the core team cannot do all this work. So volunteers with good hold on the product will have to come forward to weed out the bad threads