If the door on the shower cubical fits well at the bottom, very little water vapour escapes into the room, if you cook with an induction hob then the fuel is not adding to moisture in the room, and the automated boil and simmer reduces moisture into room from food being cooked, and if you use hot air central heating you will need to actually add water as the house becomes super dry and one is forever getting static discharges.
We can also use heat recovery units, again giving ventilation without cooling house.
However the problem is not loss of heat, but negative air pressure, one can't ensure all fans are off before any open flue fire is used, where there are no open flue fires in the building no problem, but where there are it is so easy to suck in fumes, even without any fans there are dangers, I remember returning my friend home and him having to open windows and doors in the winter to let the cold air out before lighting a fire, until that was done one could not get any draft on the flue.
Fans to remove water vapour are not required in many houses, only when poorly fitting doors or curtains are used on the shower cubical causing a chimney effect will the room fill with water vapour, with no shower curtain or door there is no problem as with mothers old wet room, and with doors that fit well at the bottom there is no problem as with my house. There may be the odd time I want to boil some thing for an extended time, but rarely do we have a problem in an electric powered kitchen.
Now to fit fans to remove odour is another matter, yes can see point in that, but water vapour no.