One problem with this style is that if you copy any text from this website you will have trailing spaces after each paragraph. To avoid that you have to close the tags (or open the next one) directly after the text.
Sure, if a trailing space in copied/paste functionality or precise :after placement is important then you'd need to modify the ending tag placement... but prioritizing that use case seems like a premature optimization. I don't think that makes a drastic difference. Compared to markdown, you've still got a heck of a lot more formatting flexibility without changing the rendered product.