Currently the policy is that all off-site resource recommendation questions are off-topic. As far as I know guidance made in chat by a community manager doesn't change community policy. While Stack Exchange, Inc. can set policies that we must abide by if want to use their services, I don't think anyone is arguing that the chat message by Shog9 was meant to be the announcement of such a policy. Instead I think Shog9's chat message was addressing how old posts should be handled, ones from before the change in policy to disallow resource requests. Generally the view has been that "good" questions that are no longer on-topic shouldn't be deleted.
On the other hand if it was meant to suggest a change in policy on how new questions are handled, I would disagree. It would require people to make a subjective decision on whether a question was a request for a canonical resource, and thus has only a single well-defined answer. I think it goes against the spirit of Stack Overflow to make moderation decisions based on what the correct answer to question is presumed to be. Off-site recommendation questions with only one valid answer would also suffer from the problem that these answers are pretty much fundamentally are going to be low-quality link-only answers.
The problem with assuming the correct answer shows up all the time with duplicate close votes. Someone sees a new question, decides that it has the same correct answer as an existing question and votes to close without considering all the potential answers. Instead of the community as a whole deciding what the correct answer is, it's just five close voters deciding to disallow the posting of other potential answers. By changing the policy allow requests for "canonical" resources we'd be asking people decide that there is only one possible correct answer that everyone would agree on. Deciding what the correct answer should be is something that should only be done through up/down voting.
The biggest problem with this suggestion though is that even if there's only a single correct answer that everyone agrees on, it'll just be a link only answer and suffer from the same problems they have. The link will go stale eventually making the answer useless until it gets fixed, if it even can be. Such answers also don't really add much value to the site. If everyone actually agrees that there's a single canonical source for a resource, then there's good chance the resource itself will appear in search results ahead of any question asking for its location.
Another problem is that the answer will likely change over time, possibly so there's no longer a single well-defined answer. A new version of the resource could get a new link, while the old link for the old version remains valid. Maybe the resource is abandoned by original maintainers and there's no longer an official source for it. Maybe there will be new links for different regions or different languages.
Finally allowing canonical resource questions as exception also creates weird situations for moderation. If multiple answers disagreeing on link to the canonical resource get posted, what should happen? If the answers aren't all bad, should that be taken as a sign that there it isn't a canonical resource question and the question closed? That would create the perverse situation where a question should be closed because its receiving good answers. If the question generates a lot of spam answers, what the existing close reason is meant to prevent, what should happen? What if a question generates answers giving unofficial links that work behind the Great Firewall or bypass geo-blocking or paywalls?
It's easy to say to just leave it to up/down voting handle situations like these, but that apparently didn't work with off-site resource questions generally back when they were permitted. These canonical resource questions can still easily generate spam, and even opinionated answers from people who think some alternative link is better.
I don't think having a single well-defined answer works as a justification for allowing an exception to the off-site resource recommendation question rule. Arguably such a justification would justify locking canonical resource questions after someone posts the presumed valid answer, since any further answers could only be redundant, wrong or worse. This is why I think such a justification goes against the spirit of Stack Overflow. It's bad enough that most of the "good" off-site resource questions from before the policy changed have had to locked or closed to prevent them from attracting more spam and junk answers.
Cody Gray's comment to Emo de Weerd's answer shows how answers giving links to resources, canonical or not, can and do work well on Stack Overflow, even if questions asking for them do not. Broadening the question so it doesn't assume a single answer both allows for competing solutions, including ones the original poster might not of thought of, and requires that good answers giving links to resources provide justification, making them not simple link-only answers. Questions like these fit Stack Overflow much better, and often require just a small change in phrasing from the off-topic version.
