I'll argue that paragraphs are not just visual formatting hints. Like <em>, they impart semantic meaning. Text within a paragraph is closely related and should not be scattered across the page or broken up by other elements. Just like <h1> is more than just "bigger and bolder!"

There are other tags you could've chosen that would support your argument. <div> for example is pure layout, so I'm not saying your argument holds no water, but you put the parenthetical there and it seems either poorly thought out or lacking in perspective.

I think the key here is that there was initially no CSS and it was required to have a way to assist the readability of the content and so layout tags were added, but I'd argue that's an artifact of how the web evolved and not the purpose of HTML.

If appeal to age is an important factor, I've been using the internet since before there was a "world wide web."

I don't know why I can't make it stop inserting these close tags. Probably a client bug.