I think the time spent on writing a summary for each paragraph could be better spent editing the paragraph to its essence, such that a summary isn't necessary.
In a typical blog post, the summaries shouldn't be necessary. A good use case for Collapsible Blogging is when you are listing multiple items or events, and the reader may only be interested in reading about one or two. Then the reader can choose to expand just those. May be better as Expandable Blogging rather than Collapsible Blogging.
I'm going to try it out this way and see what people think.