The odds of replacing markdown and all it's issues seem nearly impossible given its ubiquity and I've run into many of those problems but, this seems just as arbitrary in many ways,
For example:
> Block-level elements can't interrupt paragraphs (or headings), because of goal 7
It then goes on to show they do interrupt paragraphs
- this then - this other thing
vs
- this then
- this other thing
The 2nd is 2 list items but it's just the first with being interrupted by a block-level element.
I think you're missing the point (or I'm missing yours). I want both examples above to be one line item, not 2. djot says a blank line is required to start a new block but then sabotages itself by making an exception for list items because the author wants more compact lists. I'd prefer no compact lists rather than strange exceptions to the rules.
For example:
> Block-level elements can't interrupt paragraphs (or headings), because of goal 7
It then goes on to show they do interrupt paragraphs
vs The 2nd is 2 list items but it's just the first with being interrupted by a block-level element.