Does Google Discourage the use of WordPress Permalinks?

A recent blog entry by Google’s Search Quality Team members Juliane Stiller and Kaspar Szymanski somewhat confusingly gives the impression that Google does not like WordPress-style permalinks.

Does that mean I should avoid rewriting dynamic URLs at all?
That’s our recommendation, unless your rewrites are limited to removing unnecessary parameters, or you are very diligent in removing all parameters that could cause problems. If you transform your dynamic URL to make it look static you should be aware that we might not be able to interpret the information correctly in all cases.

A number of bloggers, including Sophia Lucero at WordPress Philippines, draw the conclusion that WordPress permalinks are harmful to PageRank. However, the specific concerns mentioned by Stiller and Szymanski suggest they are not actually criticizing the standard use of WordPress permalinks.

Instead, the authors’ overriding concern seems to be static URLs that “could cause [Google] to crawl the same piece of content needlessly via many different URLs,” and the examples they give are mainly of search queries.

That’s not at all like a WordPress permalink for a blog post. A WordPress post has a one-to-one relationship with its permalink, meaning that only that content will be found at that permalink and that post will not appear at any other permalink. Or at least that’s the way things should be on a WordPress blog: for a while SEO experts have recommended that the complete content for each blog post appear only at an individual post’s permalink. In practice that means making sure that category archives, monthly archives, and the like should show only excerpts of a post, not the complete text. Most modern WordPress themes do this, but some, especially older themes, do not.

The Google article gives a number of bad examples of “dynamic” URLs written as “static” URLs, including this one:
www.example.com/article/bin/answer.foo/en/3/98971298178906/URL
The problem with this, say the authors, is that when crawling that link it is “difficult for us to understand that URL and 98971298178906 have nothing to do with the actual content which is returned via this URL.” (Here “98971298178906” is a session id). The authors don’t even recommend simplifying the URL to something like www.example.com/article/bin/answer.foo/en/3:

Although we are able to process this URL correctly, we would still discourage you from using this rewrite as it is hard to maintain and needs to be updated as soon as a new parameter is added to the original dynamic URL

Again, the concern seems to be that the bad “permalink” example does not have a one-to-one relationship with the content. “98971298178906” is particular to the site visitor, not the site’s content, and even “answer.foo/en/3″ could change when that answer is no longer the third one.

So the main lesson a WordPress blogger should take from this is the old lesson of SEO: avoid duplicate content. WordPress permalinks that are one-to-one with their content and have relevant keywords are good for SEO. They combine the benefits of static URLs mentioned by the authors, such as higher click-through rate, without the deficits.