What is the point of an arrow key highlighting individual blocks if the individual blocks aren't editable and don't have any actions associated with them?

I don't know much about Notion, but if it's trying to be a platform that allows you to share notes and documents, its keybinding ought to be rethought. These are really bad shortcuts for a document presentation platform.

And if it's not a document presentation platform, the author shouldn't have used it that way.

If someone linked me a document that was a read-only Excel file where every paragraph was a different cell, I'd complain about that too -- because the content doesn't fit the medium it's posted in.

From a content perspective, this is a document masquerading as an app. What about this page is an app? I can't edit it, there aren't any dynamic calculations happening, the data isn't clearly separated into a table format. When I click to expand a section, I get a loading icon... and then pure text pops up that could have just been embedded into the page from the start. There's nothing that distinguishes this from a normal webpage except that the shortcuts are unintuitive.

Go visit that "app" and use the arrow keys and mouse clicks, and form a coherent theory of how the arrow keys do something sensible. arrow down moves a highlight cursor down the page, until you click, at which point highlighting disappears, and arrow starts scrolling the page, or does nothing, depending on...something?