The clutter is visible, but the more fundamental factor is the density of clutter they can live with. Add space, and soon there is extra clutter to fill the extra space to the same density. What these people actually need is less storage space, so that they are forced to get rid of junk. A similar phenomenon appears in the technological revolution at work. But what actually happens in the employment market is that more is expected of each worker, with the result that people still in work have to work harder than ever.
Work expands to fill the worker's capacity for it.