If the feature is simple enough, it is possible to illustrate it in a few sentences. I am just speculating at this point, but if the discussion went like "hey,

If the feature is simple enough, it is possible to illustrate it in a few sentences. I am just speculating at this point, but if the discussion went like "hey, I think in Markdown, if the users enters a code-block, we should treat everything literally and not escape anything. This way users can just copy-paste code and expect it to render exactly like the raw text". This is clearly spec'd and has clear expectations on how it should behave. No implementation details of course which you wouldn't expect from a product manager in most cases as well.