There are many old questions that would be closed, if they get asked again. But what should we do with them? Some new users asked too broad or subjective questions and use these old questions as a reason not to close their questions.
Old questions which were once accepted but now are not on-topic can always be locked by moderators with a note that explain they are there for historic reasons.
For example, this one:
which accidentally is the first question ever asked on Travel-SE. It's pretty clear why this question has been closed, and can serve as a guidance to new users as well.
If you notice an old question which hasn't been closed (but should, under our current on-topic policy), just flag it for mod attention, explain why, and we'll take care of it. There's not much more we can, or should, do.
If you see an old question that should be closed, the first thing you should check is whether it has useful answers. If the question has useful answers, try to find a way to edit the question to make it suitable. If the question is old, answered and unsuitable in its present state, don't worry too much about respecting the intent of the original author: the top priority is to salvage the answers, and if it takes a radical edit, so be it.
Sometimes there's no point in keeping the answers around. If the answers only repeat what can be found all over the internet, or if the question is fundamentally off-topic so that the answers cannot be presumed to have been voted on by experts, or if the question is intrinsically opinoin-based and the answers reflect this, then just vote to close the question. It will enter the review queue and be promptly closed if others agree with you.
If a question has been closed for a while (two days is the very minimum, but on a slower site you can leave it off for weeks), it should be deleted. Closing is a temporary state. If it has been demonstrated that a question isn't going to be reopened (possibly after an edit), the question should be deleted. This is the normal fate for a closed and unredeemed question. Leaving closed questions as an example of what not to do doesn't work.
Old questions can be locked as historical (it takes a moderator). This is not the normal fate of an old closed question: it should be reserved for a handful of questions that have actual significance, such as having been linked and circulated extensively. Don't put a nice frame around garbage: if it's bad enough to warrant closure, it doesn't belong on the site.
There is no point in closing these questions. It is possible to vote for closed questions, there can be comments and they can even be edited. In the latter case they will then even reappear on the top of the pile
What would be the aim of that? If you think that a question does not belong here anymore, it should be deleted or moved to another place. If you want to avoid that it reappears on the top of the pile, a question can be blocked. But that's annoying for the persons who asked and answered as they won't be able anymore to correct a mistake or update things. Not a great idea ...