Google Ranking Factor – Expected content
While I haven’t tested this in any way, a negative user experience can result if there are some basic content elements missing from the website such as content phone number, email address, enquiry form, contact page, terms and conditions page, etc.
The absence of some of these may even break laws or may be challenged in court as being required. Some sites therefore should have certain page content types present. An eCommerce store should have terms of sale and guarantee for example.
Google is aware of what type and genre your website belongs to, and can easily detect if you have a payment gateway in place, a product catalog, and a terms and conditions page.
I believe there is an element in the algorithm that is designed to detect the semantics of such pages and report them as somehow sufficient or insufficient. A negative consideration probably results if expects content elements matching the site type or genre are missing. That said, I am in the habit of making such pages ‘noindex’ so their content remains undiscovered if Google honors the noindex request, so I would expect this type of consideration is very small.
I have no evidence to suggest that allowing Google to crawl my terms and conditions page will improve my rank, however I suspect the dilution effect from off-topic content may have a larger negative effect than the absence of that content.
In any respect, if expected content elements are missing or hard to find for users, expect that Google’s AI system will have some development in place to detect the same issues.