Very true Alan.
However, whether a glorified wallpaper stripper (steam), HWE or ozone is used it will only touch the tip of the iceberg, most mites will be far away from the surface of mattresses and upholstered furniture and unaffected by any such cleaning process.
There are very few mites in carpet, by comparison.
A carpet though, will hold fall out of faeces from furniture and beds, which is the main concern, this is trapped in carpet fibres and held safely out of harms way, and is removable by cleaning and treatments.
Hard floors will allow it to be disturbed constantly making it airborne and in the breathing zone for long periods. Even the act of mopping etc a hard floor results in much disturbance causing most of the offending small particulate dust to be airborne and not removed.