I agree, see Support pandoc line blocks - #2 by Moonbase59.
Supporting fenced divs would also make it easier using things like pandoc-latex-admonition:
---
documentclass: book
pandoc-latex-admonition:
- color: firebrick
classes: [admonition, danger]
position: inner
linewidth: 4
nobreak: true
- classes: [admonition]
nobreak: true
---
::: {.admonition .danger} :::
Nunc maximus libero urna, non pulvinar sapien volutpat sit amet. Donec sit amet leo malesuada, euismod augue ac, fermentum sapien.
:::