I think there's roughly 3 types of closure:
Question that are completely unsuitable for the site because it's in the wrong language or is about some off-topic subject like gardening. These questions are expected to be closed and never re-opened. We should probably keep the ability to close these (unless you want them to be handled entirely by mod flags?). Personally, I think the new "advice" questions should also be close-able like this.
@Dharman has a comment on this saying
An off-topic question is one where we cannot provide an answer because it's out of our expertise area. Whether it's closed or not, chances are it's not going to get a good answer here.
I disagree here - mainly because people will answer off-topic questions and that kind of encourages others. Dropping this type of closure essentially makes all subjects on-topic.
Questions are considered unanswerable because they need an MRE or something similar. The hope is that these will be improved and reopened, however if those are closed then it can be a frustrating experience getting them re-opened.
I also think people are sometimes too insistent on an MRE and in a lot of cases it is possible for a subject expert to answer as-is. (I'd argue this also applies to the staging ground to an extent and maybe we're overly strict about questions needing to be "perfect" to graduate.)
I'd be OK with these being left open to be answered or age into non-existence based on their merits. It removes the frustration of trying to get them reopened, and if they are actually answerable then they'll get answered.
Duplicates. Again can be a frustrating experience if the asker believes that the question is not a duplicate (either correctly or incorrectly).
I'm less clear on what to do about these - they fall somewhere between the two other cases. I think that accurate closure of duplicates is a good thing but also that it can be frustrating.