In my answer to Are Americans more likely to be monolingual, I cited a reliable source (a Gallop poll that directly measured multilingualism) to provide the statistics being asked for regarding Americans. Another answer had already cited the statistics for Europe, so I didn't include those. Yet, my answer was deleted as "Not answering the question" because it didn't directly include a comparison to other countries. That seems like a bit of an overreach. At the very most, a comment asking to specifically include a comparison seems like it would have been a more appropriate approach, though even that seems pedantic at best. Should answers really be deleted simply for failing to replicate information that has already been given in another answer, even when they provide relevant, reliable information to compare with information in answers already given? Specifically, when that information DOES help answer the question?
Answers don't only need to help answer the question. They need to actually answer the question.
While the answer is deleted, you can edit it to include the full comparison and then flag for undeletion.
Alternatively, you could suggest an edit to another answer to include the additional data you found.
Each answer is judged on its own apart from any other answer.
Your answer must be supported by references, but you only provided a link about the US in your first paragraph
While we might debate whether you need to repeat the information present in the other answer, in the first paragraph you only speak about the US data, without comparing it at all to the rest of the world.
The rest if the answer, most of if, is about why the claim might be true, and it has no references.
As it stands, the answer does not attempt to answer the question, but it simply elaborates on the claim.
Unreferenced answers are normally marked as such while we give time to the authors to add in support. Your post, unfortunately, was not merely not referenced enough, but was not answering the question.