Based on what I have seeing so far, I can't give an opinion about the closing habits in SU, but ...
Closing questions doesn't interfere with providing help and serve people.
- Users with rep >= 5 can post in Meta. If they need help with the reopening process beyond what could be handled in comments, they could make a post in Meta.
Recent case barely related :- How to fix an unfocused post, that I thought was pretty well focused
The OP has rep = 1. Their question was closed showing "needs more focus", but it's off-topic. This shows that an OP with low rep is able to post a question on Meta and receive help / be served.
- How to fix an unfocused post, that I thought was pretty well focused
- Users with rep >= 21 (they should have earned 20) can participate in chat.
- Super User mods (at least a couple of them) are frecuently active in the chat, and there is a chatroom about Super User moderation questions.
- If they need help with the reopening process beyond what could be handled in comments, are in the mood for chatting and find the mods active in the Super User chatrooms, they might ask for guidance.
- Closed questions can be commented by users with rep >=50
- There are many users that might leave a comment into closed questions to help OP to improve their questions, help to learn the ropes of Super User, etc.
- ...
I recently was pointed to this question. Regarding the three cases presented and others linked in comments, unfortunately some of them are now deleted and I haven't enough reputation to see deleted posts.
Case 1
I was able to see the Case 1. I think that it's not a good fit for this site and I'm a bit surprised that after 7 months it doesn't show any edit / update from the OP, it's still open and with a positive score.
The question isn't about solving specific problem, it's about "understanding someting". Regarding the research reported by the OP, IMHO it's too brief, there is no mention of any related SU post, there is no mention of any reference. While lenght is not a criteria to decide how to vote usually short questions comes from people that have a high understanding of a topic and that is noticiable by the words used and synthesis capacity shown, from people that didn't spend enough time searching / researching or from people who like to post "seed questions".
A seed question (aka conversation starter / ice-breaker) might be good for Area 51 proposals or a closed stage but not for beta / graduated site.
Case 2
It is deleted. I will skip commenting about this one.
Case 3
It's unfortunate that the question had some "misleading" comments, but it looks that the community have handled this case properly.