It would be nice to be able to use call out to highlight important points when making a post/question.
I could see this being helpful for announcement posts where you want to control the formatting to have more impact to the audience, but not so much for end users in a "Share an idea" style spaces. Is that what you had in mind?
These are sometimes called "admonitions" e.g. https://mystmd.org/guide/admonitions and are quite popular in documentation tools.
