I know they're slightly different, but this reminds me of Workflowy[1] which pretty much runs my entire life right now (todo, projects, journaling, brainstorming, informal databases, bookmarks). In looking at tools like this, it's hard to know where the line is between simple functions that you then use to create abstract features, and more complicated interfaces that define features explicitly. It's a nuanced thing. With Workflowy, the simple list and tag interface can do much of what Notion does (of course, minus the great design and multimedia support), but you really need a formal workflow and need to stick to it to make it function well. Whereas Notion kind of designs those patterns for you, but at the expense of some interface simplicity. I feel like Workflowy demands more of a unix philosophy to achieve Notions features. You'll need to chain web apps together. For example, you can use hyper links in Workflowy to link to files in dropbox, or host images on some other site and audio/video on another, where Notion puts in all in one spot. Very cool.

I can definitely see this as a great tool in the classroom for creating interactive discussions. Copy a template for each class and you can have everyone collaborate and focus on the discussion, not taking notes (or better still, take notes in the collaborative page itself, things that aren't originally there), and then after you have a record of everything which you can share across all students and with different classes.

[1] https://workflowy.com/