Comment by leephillips

It does make it less useful, in an objective sense. Before the web, the practice of linking to other work, through footnotes, references, or just mentioning it in the text, was essential for anything to be taken seriously, and an absolute requirement for any scholarly publication. The web is, potentially, a wonderful evolution of this custom. You’re right about some commercial sites avoiding outbound links, but none of the ones I write for; all my editors encourage it. And there is no excuse to find this tendency to isolation on a personal site. I tend to avoid reading, and especially linking, to resources without good outbound links.