Trusting my "personal knowledge" to a proprietary tool seems like a fundamentally bad idea to me, and no amount of clever features is going to fix that.
Best self hosted tools are Org-mode and nValt.
Neither have full feature set, or work collaboratively, but nvalt in particular gives a good 80/20.
We export to plaintext markdown that reads well in either, planning export to org mode with enough data for a good elisp hacker to build parity of main features -- will do sooner if we know there are takers for that.
Have seen cool analysis of JSON export in Wolfram Alpha.
I should go back to a folder of .md files and todo.txt (http://todotxt.org/). Right now I'm using Evernote and Todoist but both of them ship my data off to the cloud - and I have no clue how secure it is. And sure I could do my due diligence but the companies are neither required to, and/or forbidden to reveal who has access to the data.
Lots of self hosted options that are much better than evernote or todoist. Org mode for one.
Worth learning emacs for that.
If you do any sort of public writing, you could use it for your writing process since that info would be private eventually anyways. Or you could expand that idea and include anything which you would be okay with being public.
For example, I may not have a reason to share a snippet from an article, but I wouldn't be bothered if it became public. I may also not be bothered if notes on that snippet were shared. And maybe if I did some writing for myself for understanding a subject, then that might be fine as well.
That's pretty much how I use the app.
Well, as soon as the encryption comes this product will be usable. Giving my personal data to a non open source note taking project without any encryption capabilities is a big no.