I know what you mean. I've made comments over the years to Slashdot, Soylent News, HackerNews, Disqus, WordPress blogs, Wikis, various other special sites, and so on and would like to see that all together and be archived -- especially when sites disappear. It's sad that people made all these centralized web services (often to make money by getting between people and their data) and thus displaced a lot of email instead of people making email better. There is a lot to be said for a local email system like Thunderbird as a knowledge base that goes back for decades. That is true even if email tools could be better if they were more generalized or if they had easier ways to publish stuff from email to the web and ingest stuff from the web back into to the local system. Some related ideas by me from 2015 which I am still working towards on-and-off in my spare time:
https://pdfernhout.net/thunderbirds-are-grow-manifesto.htmlMy latest experiment (in Mithril/HyperScript/Tachyons/Node.js) integrates a file browser, markdown viewer and editor, and email viewer (although it is all still very rough): https://github.com/pdfernhout/Twirlip15
But ultimately what we probably need more than tools are simple and popular standards for encoding information that can be linked together. Email (in MIME format) is one such standard but it is fairly complex. Maybe a JSON schema or RDF schema for linked information might help with that. Or something like tags or RDF triples embedded in Markdown -- something I started playing with in Twirlip15 (inspired in part by Foam).
Code for a foam-like "Ideas" app using markdown, triple parsing, and Cytoscape: https://github.com/pdfernhout/Twirlip15/blob/aa75ed1be5dc4a7...
And one example file: https://github.com/pdfernhout/Twirlip15/blob/792b067c30c7846...