I think it's a matter of accessibility, it is a reasonable assumption that someone writing code wants to consult the entire internet thus if the relevant manpages are not indexed by search engines then they won't find the documentation. Doing minimal SEO and publishing sitemaps is quite important. I've seen way too many institutions wondering the same question "Why are people reinventing the wheel?" when the answer is that simply having a website is not enough to be reachable.