I was surprised to discover that I can’t perform actions in vintage mode on paragraphs or sentences. For example I can’t visually select a sentence: v i s. Nor can I delete a paragraph with: d a p

I must be missing a simple solution, no?

You would have to write a small plugin to select a sentence (probably using view.find() to get the end point and using the cursor as a start point). There is a built in command for paragraph selection. So you can create probably create a macro the runs expand to character selection, followed by a delete, then bind that to a keyboard command.