For a lot of people, humidifiers only get brought out when theyre sick, so the hot wet air soothes their lungs and they cough less...

Then there was my grandmother. She had both in her music room, to protect her piano and custom built harpsichord. They were set to keep the humidity in a fairly narrow range to keep her from needing to retune.

The dehumidifier was mounted on the wall, with a hose running into the tank for the humidifier below it, so it kept it topped up with the h2o pulled from the air on rainy days, with another hose running out of that tank at about the 1 gallon mark, that fed through a hole in the floor to the basement sink, to dispose of excess water. Both were wired up to an old school analogue hygrometer, with a control circuit powering each unit when it fell outside of its respective range.