I have not yet been able to figure out if that's a typo or glitch in the software in the listing or if it's some kind of rich folk trend. I've been on the sites a lot lately looking at property and see that a lot on higher to outrageously priced homes, so am leaning towards "rich folk trend". Maybe private bath in every bedroom and then a common bathroom or two. Also a lot of rural homes with big shops next to them have a bathroom in the shop.
Not even for the ultra-rich. The trend now in "up-scale" houses is that every bedroom has to be a suite, with its own bathroom. Then you add in one or two for the visitors (not overnight guests, the casual visitors and dinner guests), and maybe another for the shop or garage, and the count climbs rapidly.
My uncle did basically that when he inherited my grandfather's summer house in Maine. He took a nice, semi-rustic cottage that had five bedrooms and two mathrooms, and remodeled it to four bedrooms and either three or four bathrooms. (I think three -- there was one bedroom that didn't have any adjacent space that could be made into a bathroom.)