Because it’s easier to dust, hoover and polish if everything’s tidied away off floors and surfaces?
Not that I have a cleaner now, but when we lived abroad and I had what they used to call a ‘houseboy’ (yes, I know) I did try to tidy up for him.
When I first had one, though, supplied by dh’s company, I used to feel guilty enough to start doing some household job while he was there - e.g. cleaning the windows. But he’d take that as a reproach (‘I do that, Madam!’) so I soon learned to chill.