Personally, I've tried maintaining a personal knowledge graph and it's...not for me. I find having to process everything digitally and dealing with the sheer amount of information presented to be too overwhelming. I much prefer notebooks, where I only ever see "one thing at a time" even though there's a sea of information in there. The only substantial benefit digital tools provide over notebooks, to me, are hyperlinks, and that's even marginal if you mostly reference only either your own notes or complete books (vs. websites, at which point it becomes substantially more useful).
Notebooks are still way faster for information capture, have no restrictions in terms of formatting, don't waste time with matters of using separate commands/ui/concepts for organization: tagging, folder structure, etc. Sure no hyperlinks but it takes 5 seconds to flip through pages to find things if you use some personal approach to indexing. I don't think any digital counterpart has really surpassed pen and paper when it comes to private notes--sharing notes, on the other hand, does seem like a good fit for digital tooling and I'm curious to see if the noosphere will beat out tools for this already built on http