You're of course correct about the percentile v. percentage difference, but it's worth highlighting that the article is only talking about landed wealth, which

You're of course correct about the percentile v. percentage difference, but it's worth highlighting that the article is only talking about landed wealth, which presumably distinguished the old money from the nouveau riche. So a more analogous (if silly) modern equivalent might be to talk about percentile of net worth held in cryptocurrencies or meme stocks.