> You contradict yourself. Is it "just a new hype-cycle," or is it "new apps, new technologies, and a new mix of features?"
The concepts are old and have a new hype. The apps are new. But generally, it doesn't matter much for the user whether you have some old-school desktop-app with gtk or Qt, or a "modern" electron app, or some webapp on your own server or some service in the cloud. At the end it's all the same ideas and concepts in different colors and flavors.
> If it's the latter... isn't that substantively different than what we had before?
That entirely depends on who is "we". We which are all users? Or we the old users? Or we the young users? Or we the new users? I'm not saying that there is not development or change, just that this is nothing new, or even a new development. This has going for a long time, it just reached a new cycle and and a new generation of users.
> Outliners have quite the fandom, but my issue with the traditional outliner is that they often trap data in outline form. Sure, most good outliners offer export options. Unfortunately, the second you've taken data from your outliner and exported it, you now have two versions of your data, and you've lost.
This is a fundamental problem of every app and space. But interoperability does exist here and there, it's not just exports.
> Logseq (and Obsidian) have changed this.
Not really? They only established a common foundation for interoperability. Which is also what other apps are doing to some degree. But you still have limitations by everything which is not covered by this foundation. For example, can Logseq handle dataview-syntax? Or generally any obsidian-plugin has it's own special syntax? What about other markdown-editors? How much do they support the special syntax used by obsidian or it's plugins?
True, the markdown-space has now a healthy movement toward interoperability and gains many nice functionalities. But it's not like this is especially new. And all those features also existed before Markdown in some app, in some way or another. Nothing is really new here. What's happening is that a new platform is growing, collection nice stuff from the collective pool of abilities, and a new consolidation is happening. This happens all the time. Sometimes it works, sometimes it dies.
Funny enough, the WWW was one of the first and most successful of this movements. And markdown grew from this as a simplification, to now grew into the same space where WWW started and obsidian now moves toward too, just in a different flavor. This whole "new" movement is just replicating where others were already before in different cloths.
> Finally, a single document _is_ an outline, a backlink, a data source, a webpage, a presentation, and so on...
So has Org-mode 10 years ago, XML 20 Years ago. HTML 30 years ago. More or less, the numbers may be a bit off.
> It's more than hype for me.
Good for you. I'm not question that. Just saying this generation is not the first one having that.