If someone comments on a generic topic, then does it matter how long ago the thread was started?

Me, I just open a link to the site, click on "Bass Guitar", see what threads are active and respond if I think I have something to say.

If there is a policy against old threads, then would it be possible to have a process which goes through and locks threads which have been dormant for a specified time?

I think that slapping people down because it is an old thread is a bit heavy-handed and slightly offputting.

That's my tuppence worth...
Posting in long dead threads (also referred to as necroposting) can be problematic when users revive an old thread to answer someones ten year old question or put their two cents in on a conversation that has long been over. Often times the original posters haven't been active on the forum for years or their topic has long since been resolved. It clutters the forum with threads that have long been irrelevant. If you search up a thread and notice that it's been inactive for a long time, please refrain from posting in it.

TL;DR It's one of our forum's rules. I would recommend reading them.
Composite Aficionado

Spector and Markbass
Thanks - looking at the bass forum rules, they state:

Rule #4: Do not necropost or “bump” dead threads.

What is necroposting, you may ask. It’s the resurrection of a thread that is months to years old that has lost any sense of relevance. Good example? A thread from two years ago where someone asked about suggestions for a good metal bass and you feel compelled to comment so long after the original post, that it’s irrelevant to the thread starter’s original purchase decision. Yes, I think after two years the poor guy has made an informed decision and doesn’t need your input. The thread will be closed and if you make a habit of doing this, you will get a warning. Want to raise the dead? Find some place other than the bass forum to practice you skills.

The clear wording there is "and has lost any sense of relevance"; now obviously some threads are time-specific (eg. "Is this guitar in my local thrift shop a good buy?" from 2003), but I was referring to generic ones (eg. how to do vibrato on a bass), which are as relevant now as when someone first asked the question in 1957.

So, my point is that answering an old thread should not be an issue per-se, but rather only if the content and relevance of the thread is specifically time-limited.

Incidentally, I'm hopefully discussing this in accordance the other rules there:

Rule #7: Arguments and debates will be allowed by all means.

As long as in no way are they personal battles. No “your band sucks”. No “you suck at bass”. No “you are a stupid s**t and you don’t know what you are talking about”. See rule #2.

Rule #2: Respect. Have it.

Respect your fellow bass forum members. Yes, the bass forum members are a fun and sometimes impertinent bunch (particularly the regulars). If a regular knocks or pokes fun at a regular) the warnings will not ensue, because no harm has been intended.

However, thou shalt respect your fellow bass player and his/her particular opinions on players, gear and other assorted bass like things. Don’t call them an idiot or question their particular sexual orientation. Don’t make racist remarks because they like a certain distortion pedal. You will be warned or banned.

And as in the rest of UG, racist, sexist and other types of inflammatory comments won't be tolerated, and you will be warned and most likely, banned.

I appreciate the work of the mods - an essential and often thankless task, but I'm just giving feedback as a user, saying that killing conversations is (ahem) conversation killing...
The long and short of it is you should avoid posting in (and thus reviving) very old threads.

I'm closing this thread now. If you want to discuss this further please feel free to message myself or anarkee directly. We appreciate feedback and are happy to talk and get things sorted out.
Composite Aficionado

Spector and Markbass