I've wondered the same thing. I think one benefit is that it looks like HTML, which means it looks similar to what you see in the browser's DevTools, which makes it easier to compare and debug.
It also makes it easier to see what it's not: at a glance, the "p" could really be anything until you scan the context. The <p> isn't a string (that on further examination turns out to get used for marking up a paragraph), it is a paragraph demarkation (in vdom, but still).