According to google's wmt, two of my most popular linking phrases are "back to thumbnails" and "the rest of the story". You may have noticed that this area of wmt doesn't distinguish between external and internal links-- though I'm morally certain the algorithm makes the distinction in real life. Here we're talking about boilerplate in footers. For that matter, I think there's still a page on my son's personal site that links to me with the words "her site" ;)
Now, "thumbnail" and "story" and "site" are all keywords, at least in theory. (Keep in mind that, according to google, "it's" is a keyword. This would be nice if I lived in San Francisco and sold ice cream treats. But I don't.) But they don't convey any particular information about what's being linked to-- especially when seen out of context.
Conversely: If you go to the search engine of your choice and look up "the world's leading authority on widgets", you will find an article written by someone who is arguably the world's leading authority on widgets. The article itself never says so. The search engine deduced it from a single instance of linking text. (There are not many experts on this particular type of widget.)