Note that there is a difference between closure and deletion. Just because a question is closed does not mean it will be deleted.
Everything below is my personal opinion only.
Purpose
I can only speak to why I propose to close abandoned posts. Generally, I only even consider this close reason for users who participate infrequently on SFSE. If a question is borderline/unsalvageable, has not gotten good answers, and lacks enough generality to make it useful elsewhere, it really doesn't add much to the community.
If it's a good question that just doesn't have an answer yet, I would try to answer it, edit it, or offer a bounty to increase visibility. But I'm less likely to take those steps if I don't believe the OP will even know the difference.
When I find such a low value post, I try to close it to help improve the quality of this site. If the OP (or someone else in the community) disagrees, it's easy to pipe up in the comments to clarify that it is not abandoned, and if it gets closed successfully, any edit will place it in the Reopen queue.
Template
I do have one quibble with the pattern you discuss in your post, which is that I believe our close reasons should be fully formed sentences. So when I decide a post meets my criteria for abandonment, I will use a complete sentence such as:
I'm voting to close this question as off-topic because it appears to be abandoned.
At times I have added some additional copy about retracting my vote under certain conditions, but I never found anything that felt right.
General Abandonement Criteria
- The question was posted at least a year prior.
- The question does not have an accepted answer.
- The Original Poster does not have any activity within the last 2-3 months.
- I generally only scan their profile for recent Questions or Answers.
- If a question needs some back and forth with the OP to be improved, and they do not even visit SFSE on a monthly basis, the odds of improvement seem minimal.
- The question does not have a rigorous Minimum Viable Reproduction.
- If you couldn't even provide clear MVR a year ago, the odds you can now are not good.
- The question has a narrow focus.
- Many of the questions I vote to close for this reason seem specific to one project and do not contain generally applicable learns for the broader community.
- Those questions which appear specific to one project seem likely to have been worked around in some way or another. The project is not likely ongoing.
Bullets 4 and 5 above tend to also overlap the "specific problem" close reason:
Questions on problems in code you've written must describe the specific problem and include valid code to reproduce it. For help writing short, self-contained syntactically-valid examples, see: SSCCE.org
However, I sometimes still use this separate custom close reason anyway, either because it would have been borderline to close it as such or to highlight the fact the OP seems unlikely to return.