I don't know of such a canonical question/answer, but I will argue in favor of it.
The canonical question/answer gives us a clear place to point users to when we close a question as a duplicate. This approach is especially useful for questions that are very common for beginners in the area. With the canonical approach, we can curate a single high-quality question that captures the essence of the common issue, and know that we have one or more high-quality answers to it.
Such resources for beginners may exist on other sites, but we as a community cannot be 100% certain those sites will remain active and the content or links unchanged. With a canonical question/answer on this site, we can be certain that it will survive as long as StackExchange does.
Here is a nice meta post from the Chemistry community (my primary field and site) describing their approach to canonical questions and answers. It also lists canonical question/answer pairs that have been developed.
I am the author of one canonical answer
and one canonical question/answer pair.
This second question is a chemistry equivalent of a common question novices have. Novices think they are asking what appears to be a simple question, but the true answer amounts to the sum of the knowledge of the field. The overfitting question is similar. The problem is common. Novices may want a quick fix when there are actually a wide range of solutions depending on what you are trying to accomplish.