There's no such thing as a necro for tech related threads.
The whole point of forums is that people can post questions and answers not limited by space and time.
That means forumites and web searchers can get answers, opinions, tips & tricks, advice & guidance and discussions, etc and benefit from the experience of others over time. Sharing the experiences and seeing how they evolve is a good thing, especially for newbies.
It further means that the same questions and topics don't get repeatedly asked.
This silly notion that "necro" is somehow bad is itself unthinking and idiotic. It's far better to continue discussions in an existing thread even if the topic was first raised many years ago. The alternative is less than ideal because it spawns multiple threads on the same subject and thereby adds to internet and forum clutter.
By all means call out a "necro" on something that is obviously timebound, like "Anyone going to Vladivostok next Thursday?".
But please think about it for a millisecond and stop calling "necro" on threads and topics not timebound. Using an existing thread no matter how old is actually a good thing.