Avoid online-only aspects While the WWW is the most common destination for an HTML document, it's certainly not the only one. And even when it is on the WWW, the reader's way to access it may not be anything like yours. It can be viewed on any platform, no matter how limited. Especially important for reference documents, but also for indices and home pages, is the printability.
People still prefer a hardcopy version of useful texts.
If the text is full of explicit references to things that only work on the on-line version, the printed document becomes unusable. Not only does it assume that the user is using a mouse, it also draws the attention away from the surrounding text. A hyperlink anchor should be understandable on its own. Embed the link in the actual text, in such a way that it is not required to follow the link to understand the text.