rel="canonical" on SO used incorrectly?

Question

Isn't the rel="canonical" on SO used in a wrong way so that it prevents google from indexing every other page than the first of questions that have +1 pages?

The rel="canonical" hint should be used to point to the canonical URL when the content of the pages is identical, e.g. when the content is just ordered by another criteria or if you see the page optimized for printing.

Example:

The URLs

• https://stackoverflow.com/questions/1411394/how-to-become-a-faster-programmer
• https://stackoverflow.com/questions/1411394?sort=oldest&page=2#sort-top
• https://stackoverflow.com/questions/1411394?sort=newest&page=3#sort-top

all have the hint, but contain totally different content.

I did some site searches for exact phrases from these pages and only got results that are listed under the canonical URL.

Can you confirm this and what do you think about it?

Answer 1

I think the thinking here is that the question content is identical, so if you google for terms that are found in the question, you don't want every page of answers to appear in your search results. Instead you can go to SO and page through the answers yourself.

As to motivation, they are probably thinking that you are going to be googling for your question rather than your answer. After all, you kind of have to know what the answer is in order to search for it.

EDIT: In this question (and Jeff's response) it's explicitly stated that this is the reason (preventing the same question from uselessly appearing multiple times for the same search).