About significance of questions and whether or not they should be deleted

Personally, I think the rule is quite simple:

Always vote to delete closed questions unless their existence is making the Internet a better place.

The only tricky thing about that rule is defining what it means to "make the Internet a better place." Well, obviously anything that is spam, noise, or otherwise worthless is making the Internet a worse place, so these cannot be an exception to the deletion rule. The community consensus is strong here; everyone knows crap when they see it.

The tricky part is what should save a question from deletion (which, as Grace Note and Shog9 have pointed out, is a closed question's destiny). I choose to save questions whose answers contain useful information that cannot trivially be found elsewhere and might be useful to others in the future.

I do not see any merit in rushing to delete borderline cases.

_{Bonus chatter: there was a big hullaballoo several years ago on the Meta site, effectively dividing the community into two groups: the "deletionists" and "preservationists." Like all labels, these were not entirely apt, but they captured the essence of the positions in the debate. One group felt that questions that were once acceptable, but now fell afoul of our new guidelines, should be deleted because their presence was hurting the site—they were effectively serving as "broken windows," suggesting to new users that these types of questions were on-topic and acceptable when they really weren't. The second group wasn't quite sure that they agreed with that logic, but even to the extent that they did, they screamed about the need to exercise caution over the risk of deleting potentially useful and interesting content, arguing that those old, historical questions made meaningful contributions to the body of knowledge on the Internet, making it a better place, even though our guidelines had since evolved and we were no longer willing to take a gamble on that type of question going forward. The debate finally calmed down following the introduction of the "historical lock" feature, and now it seems to have been mostly forgotten. If you're curious and weren't there (what is wrong with you?), the only link I can easily dig up is this one.}

I'm mostly in the camp that you shouldn't fear deletion, you should fear the loss of useful content. A deleted question whose useful content is available elsewhere is good deletion. Remember, not every question under the sun should be asked here, if that means that we need to expend more effort in making the content available in a more substantial form (i.e., too broad questions broken down, opinion-based becomes fact check, off-topic becomes blog post or examples on documentation, etc.) which are more searchable and precise.

I personally hate it when off-topic but useful content gets deleted. Closure if for off-topic, deletion is for useless, unsalvageable stuff.

In this particular case, the user is not so much asking "to recommend or find a book, tool, software library, tutorial or other off-site resource" - the real question is: Can I create a SWIFT program on Windows? That is reasonably scoped and, if worded that way, probably on topic.

So it is not even completely and obviously off-topic. Deletion seems very abusive in this case.

I have edited the post and voted to undelete.

Also note if that question had less views and votes, it would probably have gone unnoticed. That is an inherent paradox: the more popular (and useful) an off topic question is, the likelier it is that some zealots will see it and want to delete it...