This use of rooms is an interesting subject because many of the articles about old people occupying houses with more bedrooms than they need is based on the way house use was defined in the past: Upstairs bedrooms, downstairs living rooms. That really does not apply anymore. However people do still use these conventions to describe houses.
In two of the houses we have owned one of the upstairs rooms has functioned as a study. The whole time we owned the properties these rooms never contained beds and were never slept in, but we still described the house as '4 bedroomed'
We are house hunting at the moment, which means scanning Rightmove even more than usual and one thing that has become very clear is that nowadays, both in new houses and the use of existing properties, room purpose is much more fluid.
Many new houses, seem to have rooms described as bedrooms scattered all over the house on all floors, while in existing properties, upstairs rooms are used as offices, gyms, workrooms, music rooms, sewing rooms. Even more so as more people work form home, at least part of the time.
DD, who lives alone, is currently buying a house described as having five bedrooms. It is a three storey house and two of the 'bedrooms are on the same floor as the living room. She sees the house as a 3 bedroom, 3 reception room house, with the other two living rooms being used as an office, as she works from home a lot, and a craft room, as she is an inveterate craftswoman - the only person I know who made her own stair carpet!
This is another thing about housing for older people. As you get older and into extreme old age, you tend to spend more time in your house and need extra space downstairs to be able to move around, change your scene and contain any interests you may have. Most retirement properties, invariably have just one big living room and only one or two other, quite small rooms.