There used to be a close reason that basically said, "too specific to this one person", and, yes, in general, we prefer that questions have the hope to be useful to others. However, there is often an underlying principle or concept within the context of the question that is more universally useful.
In these cases, it's important that the tags are accurate and that the title reflects the more general case rather than the specific case so that it is more searchable.
In other cases, they can be conceptual duplicates of other questions, and should be closed as duplicates.
For the corner cases where it is unique and very specific to a certain context, we can take it on a case-by-case basis.
For the question you linked, it's a duplicate of a variety of questions asking about password strength, as mentioned in the comments.