Block editors often become toy boxes. Every block is a chance to look like software. Quire’s test is dull and useful: would this belong on a printed page?
What passes
Lists. Quotes. A photograph with a caption. A callout that is still a paragraph. A table that a person could fill with a pencil.
What fails
Live dashboards. Reaction counts. A canvas that forgets it is a document. If you need those, you need a different desk.
The block is a way to keep the sheet honest, not a way to smuggle an app into a paragraph.
