Ventilation used to come in the form of a fireplace and huge amounts of heat going out the chimney. Can't really replicate that with modern systems unless you just want to lose a lot of energy in the process. Ventilation with heat recovery is probably the best replacement.

Then you get some people who don't understand how energy use really works and turn the system off thinking it will save them money on their energy bills. Save 20p, get mould. Not sure if that was worth it but it happens a lot.