Shouldn't headings always be block-level elements?

While setting up the example for this other topic, I was playing with the text flow around picture feature, but noticed that headings flow around the image too, much like normal (paragraph) text.

I.e.: Headings and text flow (Sandbox.HeadingsAndTextFlow.WebHome) - XWiki
There, shouldn’t Paragraph three be on its own line, starting from the left side?