Mechanical ventilation refers to just using fans. The comment you’re replying to is suggesting that heat recovery ventilators (HRV) be used to transfer heat from the warm exhausted to the incoming outside air via a heat exchanger (or cools incoming outside air in hot climates). It reduces the need for heating or cooling while still getting fresh air into the building.
No. It usually takes the form of extractors in the most humid locations of the house (kitchen, bathroom, laundry) that are connected to a central unit that vents air to the outside. Fresh air comes in through ventilation grills around the house, normally located above windows by means of the resulting pressure. No air conditioning is involved, or recirculating, though more modern (and much more expensive) units have heat recovery systems and air filters that will also bring fresh air back in.
In that case I would disagree, it’s a magnitudes bigger waste of energy and resources and causes illness (at least for me).