There have been a few of these lately... where questions are being closed (or are in the process of being closed) but are often over a year old or have accepted answers.
For example, this question. It was asked on July 4th 2017, it has a few up-votes, a couple of answers with up-votes, and an accepted answer in August 2017.
What's the value in closing old questions like this? Has our definition of opinion-based or good subjective changed?
I can't be sure, but I suspect at least some users have issues with the difference between "good subjective" and "bad subjective" questions - which isn't an easy call to make for anyone.
When I see a close vote on an older question in the moderation queue, I look at how old the question is, what the votes are, whether an answer was accepted, and the quality of the question. I don't vote as often as I used to, because as a moderator my vote is enough to finalize the action, but when a question obviously should be closed, I'll close it, and when it shouldn't, I'll vote to leave it open.
The question you linked is one I voted to leave open.
The other thing I do when I can is comment on questions that could be improved asking the poster to make changes that would improve the question so that it can be better answered and isn't as likely to be closed out. If I can and I have the time, I'll edit the question to try to improve it.
To many people, they aren't old questions. Old questions are periodically bumped by the system to see if someone has some insight into it. When people see a question that they think should be closed, they vote to close it. But they are just looking at whatever is coming up on the home page, they aren't actively seeking out old questions.
Stack Exchange is meant to be a repository of information. How old it is shouldn't be a factor in its usefulness, unless of course the information has changed. Stack Exchange actively encourages activity on old posts with badges such as Necromancer.
