Any Markdown editor, yes. But not everyone is familiar with Markdown formatting. People coming from text editors, forums, and word processors expect a single enter to start a new paragraph.

I’m using the website, and the standard editor. /shrug

I’m not aware of anyone who uses a word processor to leave a comment on Lemmy.

Even in a text forum, or a text editor, you usually double-enter between paragraphs. Single enter just looks too crowded.