A quick observation:
Something I notice when I scroll around the graph of my new MakingHistory vault folder (I typically open it as its own instance of Obsidian, so at the moment I'm writing a Daily Note in the main vault while the more specialized vault is open on the screen too) is that there are plenty of gray, empty nodes. I don't precisely feel obligated to fill all of these. Some I may delete. There are some which I will certainly get right to when I see them, because they are ideas or events or people that I've mentioned in one post that would almost certainly link to others. Joseph Priestley, for example, is an interesting character. I had double-bracketed him in a post about Benjamin Franklin, but he is relevant in other contexts as well. In addition to that "linked mention" there are already two more, in my note on Edward Royle's book, English Radicals and in my note on James Watt Jr.
When I clicked on the gray node on the graph and began actually filling in some information in the note, Obsidian reminded me of the links (this is an option you can turn on, if I recall). It turned out in this case that the couple of "unlinked references" were just additional uses of the name in the notes I've already mentioned. This is not always the case, though. Often I find there are a bunch of moments in other posts when I have mentioned a person, event, or idea in passing but haven't bothered to double-bracket it. Sometimes, reviewing my notes, it strikes me that the connection might be valuable to acknowledge. Double-bracketing the term in the note in which I had previously just brushed past it leaves a breadcrumb trail that alerts me there may be some additional connections between the ideas in those notes. To go back to my example, if Joseph Preistley shows up in unexpected places, maybe I ought to think harder about why.