There seems to be an insatiable appetite to discuss housing in Ireland, with small issues often given disproportionate prominence. The latest sideshow is about the elderly downsizing. It is true that Irish homes are among the most underoccupied in Europe, but even if this changed overnight and occupancy became more like the rest of the rich world, it would not change the main problem: the yawning gap between the supply of homes and the scale of demand for them. As the last decade drew to a close, supply and demand were matching nicely. House prices had flattened, and rent growth…