A chess question of W.T. Tutte has been closed for at least 5 years. The only argument given for its closure at the time was that a moderator saw it as a question of chess strategy. I think the first phrasing was not clear. Most of the answers (including the green-ticked one) are indeed "chess answers".
However, it is not a question of chess ...
After a question is closed, it can still be viewed. So the view count can still go up. You can still edit the question, if you think you can make it into an acceptable question. Then (with enough votes) the question can be re-opened.
So "closed" is not the same as "gone and forgotten".
Have you read the tour?
MathOverflow is a question and answer site for professional mathematicians.
Your question does not qualify for this; hence it's downvoted and closed. For more details, see What topics can I ask about here?
Status: [REOPENED] Thank you!
Request to reopen How to obtain the rational solution of a linear system efficiently?.
In light of recent discussions about being more welcoming to good faith questions from less experienced users, I believe this is an example of a question that was too quickly closed and not given due consideration. I had previously voted to ...
It doesn't show on the homepage, but you can find it via the list of questions. This is status-bydesign; questions with a score of -4 or lower on the main site and -8 or lower on the meta site are hidden from the homepage.
Reference: Meta sites' front pages should not hide questions with very low scores on Meta Stack Exchange
Your impression is correct: users with 10k+ rep and site moderators can see deleted posts. No, it is not too late to resurrect them, unless some extraordinary action has been applied (like a lock). But you need some high-rep users to apply undelete votes. (I'm speaking here of posts deleted by the community.)
Information on how deletion works is here: How ...
This refers to the so-called question ban and it's per site; your questions on MathOverflow do not influence your ability to ask questions on other Stack Exchange sites. Not even Meta MathOverflow; it's perfectly possible to ask Meta questions while being question-banned on the main site.
Another informative article is this Help Center article. It doesn't ...
The FAQ post "What can I do when getting “We are no longer accepting questions/answers from this account”?" contains the following paragraph:
Will a ban on one Stack Exchange site affect my standing on other sites in the network?
No, post bans are considered separately per site. Your activity on one site will only affect post bans on that one site,...