Please have a look at this question:
The answer by pQd is correct if a bit short. Someone else posted a duplicate answer and received the upvotes instead.
Here's pQd's answer (now deleted) in its entirety:
Meta Stack Exchange is a question and answer site for meta-discussion of the Stack Exchange family of Q&A websites. It only takes a minute to sign up.Sign up to join this community
pQd is correct if a bit short
The emphasis here is mine; the problem here is that the answer whilst technically correct is virtually without substance - or rather, link only. Perhaps I should explain. There is quite a "usefulness chasm" between this answer:
Try SQlite. SQLite is a sql-like database system that saves the database state to a single file somewhere on the file system, as opposed to requiring a full server. It does not have the full performance optimisations in SQL terms of full servers such as Postgres or MySQL; however, it does not require the overhead of a server.
and so on. The accepted answer contains some extra info:
It's cross-platform, self-contained and serverless.
Which the other does not.
Let's look at it from another angle entirely. Suppose I gave this answer:
You've never heard of UnicornDB. Unlike sqlite, 99% of SO do not know what it is. As an answer, therefore, it is unhelpful. Are you going to follow the link? Maybe. But the problem with links is link rot. So when the author of the project decides he/she is fed up and issues 410's to you, we no longer have an answer that was valid because aside from that link there is no information in it.
Long story short, if you want your answers not to be deleted it is best to ensure they contain more than two words and a link. Or, if you prefer it in web terms, don't issue redirects in answers.
The answer was probably flagged as "not an answer" or "should be a comment" and subsequently deleted by a 10K+ user or moderator. There is no hard-and-fast rule about how much information needs to be in an answer, but some people would certainly consider a single link to be too short to be considered a "real" answer. Providing an answer that comprises a single link is bad for a number of reasons.
Remember that Stack Overflow gets a lot of traffic and generates a correspondingly large number of flags. It would be very easy for a reviewer to see this post under the review tab and flag it without a second thought, and equally easy for a 10K+ user or moderator to delete it and move on to the next one of thousands of unresolved flags.
Shog9 ♦ has pointed out one more reason that answers like this will probably be flagged:
links are stripped from the text shown on the Review page - the answer would have appeared as, "try sqlite.", two words, nothing more.