Firstly IMO, the word "relevant" is misleading and vague in this context.
How do you define relevance to the newcomers?

Taking this thread as an example, the necro poster here seems to have
deliberately posted a detailed question as a response to "I might be doing
a How-To. Anyone interested?".

If the newcomers could know that the version difference could cause
errors, they simply wouldn't have asked the question in the first place!
That old thread talks about Sun One, so does the necro poster.

Neither has been mentioned anywhere that asking follow up questions
in a thread is considered non-relevant!

How about rewording the above quote to:

Your keyword here is I agree with you that posting a new thread is the best way and even then linking back to the old thread is a better way.

But then again, everyone has a different learning curve.

Just my

newcomers + online fora = no practical way to regulate behavior

To be sure, I am among those who are frustrated and annoyed by the behavior of newcomers. I simply don't see any practical solutions.

My current pet peeve is the "One post, never to be seen again, dilettante". It seems that we hear from one of these at least once per day. Do we need a rule to stop them? Would it work?

On topic: wrt old threads---didn't we have some traffic lately about simply closing them?

1 members found this post helpful.

You will never be able to police anything like this simply because we do not know who the 1 posters will be.

From memory syg00 (I may be wrong sorry of I am) posted and was rather obnoxious in his/her post on the issue. That was the last I saw.