Unfortunately the article is extremely sloppy with the numbers and that makes it very hard to understand what is really going on. Primarily, they keep mentioni

Unfortunately the article is extremely sloppy with the numbers and that makes it very hard to understand what is really going on. Primarily, they keep mentioning "average house-price-to-income ratio" but appear to be using average home price and median income. Both housing price and income distributions are enormously skewed. In the Unites States average income is almost double median income and that difference has been increasing over time. So right there, even if median house price to median income has stayed constant, you would notice the pattern pointed out. I don't doubt the central premise that housing prices are rising faster than income within household, but unfortunately the article does nothing to show it.